Silicone-containing polymers, compositions and improved oxygen permeable hydrophilic contact lenses

ABSTRACT

The present invention relates to novel copolymers and contact lenses made from these copolymers comprising preformed silicone-containing acrylic star polymers, graft copolymers and macromonomers, preparation of these contact lenses and a therapeutic method for treating patients with visual impairment. 
     Described is a composition comprising at least about 10% by weight of a preformed silicone-containing acrylic copolymer and no more than about 90% by weight of a matrix formed from the random polymerization of a mixture of monomers. The mixture of monomers comprises at least one hydrophilic monomer and at least about 5% by weight of a polysiloxanylalkylester of an alpha, beta unsaturated acid and optionally, monomers selected from the group consisting of esters of alpha, beta-unsaturated acids and crosslinking monomers. The preformed silicone-containing acrylic copolymer is preferably copolymerized throughout the matrix. The final compositions are hydrated to a final water content of at least about 10% by weight.

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 773,714, entitled novel Silicone-Containing ContactLens Polymers, Oxygen Permeable Hydrophilic Lenses and Methods forMaking These Lenses and Treating Patients with Visual Impairment, filedOct. 9, 1991, which is a continuation-in-part of Ser. No. 595,512, filedOct. 11, 1990, which is now abandoned.

FIELD OF THE INVENTION

The present invention relates to novel oxygen permeable hydrophiliccompositions for use in medical devices, including contact lenses,comprising silicone-containing acrylic star polymers, graft copolymersand macromonomers in combination with substantial quantities ofmonomeric silicon acrylate(s) and preparation of these hydrophiliccompositions and contact lenses.

BACKGROUND OF THE INVENTION

Walter E. Becker, in U.S. Pat. No. 3,228,741 (1966), disclosespolysiloxane polymers for use in elastomeric contact lenses exhibitingexceptionally high oxygen permeability.

Charles S. Cleaver, in U.S. Pat. No. 3,981,798 (1976), discloses randomcopolymers produced from the copolymerization of perfluoroalkyl alkylmethacrylates or fluorine-containing telomer alcohol methacrylates andmethylmethacrylate for use in rigid gas permeable contact lenses.

N. E. Gaylord, in U.S. Pat. No. 3,808,178 (1974) and Re 31,406 (1983),discloses random copolymers of polysiloxanyl acrylates and alkyl acrylicesters made by free radical polymerization for use in contact lenses.

N. E. Gaylord, in U.S. Pat. No. 4,120,570 (1978), describes a method fortreating patients with visual defects by fitting them with rigid gaspermeable contact lenses made from random copolymers of polysiloxanylacrylates and alkyl acrylic esters.

N. E. Gaylord, in U.S. Pat. No. 3,808,179 (1974) discloses randomcopolymers produced from the copolymerization of fluoroacrylates andesters of acrylic acid and methacrylic acid for use in rigid gaspermeable contact lenses.

K. A. Andrianov, et al., Bull. Acad. Sci., USSR Chem., No. 4, pp 467-472(1957) describes the synthesis and polymerization of OrganosiliconeCompounds containing a methacrylol group.

R. L. Merker, et al., Journal of Organic Chemistry, 21, 1537 (1956)describes the synthesis and physical characteristics of copolymers ofsilicone acrylates and methyl methacrylate.

E. J. Ellis et al., in U.S. Pat. No. 4,152,508 (1979), disclosescopolymers of siloxanyl alkyl acrylates, an itaconate ester, and anester of acrylic or methacrylic acid. The copolymers preferably includea cross linking agent and a hydrophilic monomer.

E. R. Martin, in U.S. Pat. No. 3,878,263 (1975), discloses polysiloxanepolymers obtained by equilibrating a mixture containing anacrylate-functional silane or siloxanes and a cyclic organopolysiloxanein the presence of a base catalyst and an aprotic solvent.

G. D. Friends et al., in U.S. Pat. No. 4,254,248 (1981), disclosecopolymers prepared from monomeric polysiloxanes end-capped withactivated double bonds and polycyclic esters of acrylic or methacrylicacid.

W. S. Covington, in U.S. Pat. No. 4,245,069 (1981), discloses copolymersand terpolymers of an addition cross-linked polysiloxane and one or moreacrylic or methacrylic esters of certain hydroxy or alkoxy alcohols.

W. G. Deichert et al., in U.S. Pat. No. 4,189,546 (1980), disclosecrosslinked networks prepared from a poly(organosiloxane) monomer alpha,omega-terminally bonded through divalent hydrocarbon groups to freeradical-polymerizable unsaturated groups. Homopolymers and copolymersare disclosed.

Deichert, in U.S. Pat. Nos. 4,153,641, 4,189,546, 4,208,506 and4,277,595, disclose monomeric polysiloxanes end-capped with activatedunsaturated groups which are copolymerized with acrylic acid and othermonomers to form hydrophilic contact lens materials.

Mueller, et al., in U.S. Pat. No. 4,605,712, disclose a contact lenscopolymer containing polysiloxanes of uniform molecular weightcontaining a vinyl group connected to intervening alkylene urea orurethane linkages.

Mueller, et al., in U.S. Pat. No. 4,486,577, disclose contact lenscopolymers comprising polysiloxanes containing at least two terminal orpendant polymerizable vinyl groups.

Anan, et al., in U.S. Pat. No. 4,933,406, disclose a contact lensarticle which is obtained by copolymerizing a silicone-containingmonomer of defined structure, a fluorine-containing compound of definedstructure and a polymerizable vinyl monomer.

Culberson, et al., in U.S. Pat. No. 4,977,229, disclose contact lenscopolymers formed by copolymerizing a siloxane-containing monomer andother monomers.

Nakashima, et al., in U.S. Pat. No. 4,814,402, disclose a contact lensmaterial comprised of N-vinylpyrrolidone, methacrylic acid and asilicone-containing (meth)acrylate.

A. Aoki et al., in U.S. Pat. No. 4,304,881 (1981), disclose thepreparation of styrene/butadiene "living" polymers by anionicpolymerization and coupling of these polymers by reaction with siliconetetrachloride to produce a 4-arm star polymer having a silicone atom asa core.

Yoshioka, in U.S. Pat. No. 4,990,561, disclose a wax compositionprepared by polymerizing a mixture of a methylpolysiloxane(meth)acrylatecompound containing one (meth)acryl group and three or more methylsiloxygroups with one or more vinyl monomer(s) to produce a copolymer which iscopolymerized with an organic wax.

O. W. Webster, in U.S. Pat. Nos. 4,417,034 (1983) and 4,508,880 (1985)and W. B. Farnham and D. Y. Sogah in U.S. Pat. Nos. 4,414,372 (1983) and4,524,196 (1985) disclose the preparation of acrylic star polymers usinggroup transfer polymerization by coupling "living" polymer with acapping agent having more than one reactive site or by initiatingpolymerization with an initiator which can initiate more than onepolymer chain. Initiators that could produce acrylic star polymers withup to 4 arms were demonstrated.

H. J. Spinelli, in U.S. Pat. Nos. 4,659,782 and 4,659,783 issued (1987),teaches the preparation of acrylic star polymers with crosslinked coresand at least 5 arms, optionally having functional groups in the coresand/or the arms. Group transfer polymerization being preferably used tomake the polymers is disclosed.

N. Novicky, in U.S. Pat. No. 4,248,989, discloses novel branchedsilicone acrylate monomers for use in making rigid and semi-rigid gaspermeable contact lens compositions. Polymerization occurs by randomlypolymerizing a number of monomers including the disclosed highlybranched silicone acrylates, wetting agents, alkyl esters of acrylic andmethacrylic acid and hydrophilic monomers.

Wittmann, et al., in U.S. Pat. No. 4,508,884, disclose rigid gaspermeable contact lenses obtained by the random polymerization ofethylenically unsaturated silicone esters, sterically hindered or bulkyaliphatic esters of ethylenically unsaturated carboxylic acid andhydrophilic monomers. A method of polymerization to produce the contactlens compositions of Wittmann, et al. is also disclosed.

As is true for most bio-medical applications, polymers that are to beused in contact lens applications have very demanding requirementsplaced on them. For example, rigid gas permeable contact lenses, likeother contact lenses, not only must be hard and machineable, but alsohighly oxygen permeable. In addition, these lenses must be comfortableto wear. Furthermore, these contact lenses should have thecharacteristics of good flex resistance, adequate wettability andnon-adherence to the eye. It is also important that the lenses maintaintheir shape after extended use. Finally, the lenses should be resistantto deposits of proteins, lipids, and bacteria.

In the case of soft contact lenses, these should be oxygen permeable,drapeable, wettable, durable, have adequate "toughness" ortear-strength, clarity and resistance to deposits of proteins, lipidsand bacteria.

Initially, contact lenses were made from polymethylmethacrylate (PMMA),a hard, easily machineable polymer. These lenses were reasonablycomfortable to wear but were not sufficiently permeable to oxygen.Consequently, they could be worn only for limited periods of time.Wearing such lenses for prolonged periods of time sometimes resulted inserious eye damage.

The next generation of lenses were the soft lenses made frompolyhydroxyethylmethacrylate (PHEMA) containing high concentrations ofwater. These hydrogels transport more oxygen than does PMMA because thepolymers accommodate large concentrations of water, but the lenses aredifficult to manufacture and handle because of their softness. Theincreased oxygen transport is associated with the solubility of oxygenin water rather than to the polymer per se. In order to increasepermeability of soft contact lenses, attempts have been made to increasethe water content of these lenses. However, an increase in water contenthas two disadvantages; the first is that with increasing water contentthe lenses tend to become less resistant to tearing; the second is thathigh water contact lenses tend to dehydrate rapidly when made thin. Inaddition to the above-described deficiencies as well as the fact thatthe lenses may be too soft and difficult to handle (deformable), thehydrogel soft contact lenses are very susceptible to deposits and lacktear resistance.

The most recent generation of lenses, the rigid, oxygen-permeablelenses, are made from random copolymers of silicone acrylates andmethylmethacrylates such asTRIS(trimethylsiloxy)-3-methacryloxypropylsilane (TRIS) and methylmethacrylate. These lenses have a significantly higher oxygenpermeability than lenses made from either PMMA or hydrogels. Lenses madefrom TRIS homopolymer have very high oxygen permeability but they aresoft, lack wettability, do not resist deposits well, and areuncomfortable to wear. Using TRIS copolymerized with methyl methacrylateincreases the durability and machinability compared to TRIS homopolymer,but there is a trade-off in other properties, most notably the oxygenpermeability. The manufacturer can provide lenses with high siliconecontent that can be worn for extended periods of time but are verydifficult to make or harder lenses with relatively high methylmethacrylate content that are more easily machineable but have reducedoxygen permeability.

Other monomers that have been used in making contact lenses oftenimprove one property at the expense of others. For example,hexafluorobutyl methacrylate (HFBMA) gives excellent resistance todeposits but is less oxygen permeable than are the silicone acrylates.Lenses made from dimethylsilicone elastomers (polydimethylsiloxane-PDMS) have very high oxygen permeability but are very soft, anddifficult to manufacture, extremely non-wettable, and very uncomfortableto wear.

One of the current processes for making materials for contact lensesinvolves the bulk free radical copolymerization of an alkyl(meth)acrylate, for example methyl methacrylate, with apolysiloxanylalkyl ester of acrylate or methacrylate (siliconeacrylate), among others, for example TRIS, and an amount of apolyfunctional monomer, such as ethyleneglycol dimethacrylate, toprovide rigidity through crosslinking. As mentioned above, there resultsa trade-off in properties depending upon the relative proportions of themonomers used. It was originally believed that lens materials havinghigh oxygen permeability and improved hardness and machinability couldbe made by incorporating a hard polymer such as PMMA in the bulkpolymerization of a silicone acrylate with an alkyl acrylic ester. Ithas been found, however, that PMMA is not soluble in silicone acrylatemonomers nor in their mixtures with alkyl acrylic esters; nor has itbeen possible to incorporate PMMA in the highly oxygen permeabledimethylsilicone elastomers.

Conventional soft contact lenses may be made by first polymerizinghydrophilic monomers, such as hydroxyethyl methacrylate (HEMA),glycerolmethacrylate (GMA), methacrylic acid (MAC) and N-Vinylpyrrolidinone (NVP or VP), among others into a rigid "button", thenlathing the button into a contact lens, which is finally hydrated into afinished product. Alternatively, these lenses may be cast-molded toproduce semi-finished or completely finished lenses. Although the keyproperties of a soft contact lens are oxygen permeability, drapeability,deposit resistance and "toughness", conventional soft contact lenseshave been quite limited in their ability to maximize all of these keyproperties. As in the case of rigid gas permeable contact lenses,trade-offs exist in soft contact lenses as well.

For example, the hydrophilic monomers which are normally used to makesoft contact lenses are not oxygen permeable, and consequently softcontact lenses have had to rely strictly on water content to provideoxygen permeability. The more water that is present in a soft contactlens, the greater is the oxygen permeability. For example, contactlenses having water contents of less than about 40% tend to have lowoxygen permeabilities (Dk<15×10⁻¹¹), whereas contact lenses having watercontents approaching 75% have higher permeabilities (Dk approximately35×10⁻¹¹). Although increasing the amount of water in a contact lens isan obvious way to increase the oxygen permeability in a contact lens,conventional contact lenses are limited in the amount of water that canbe present or in the thickness of the lens. Attempts to increase watercontent to levels above about 40% or higher have resulted in dramaticlosses in "toughness" or tear strength, greater susceptibility to cutsand tears and handling difficulties because of the flimsiness of thelenses. To compensate for the absence of "toughness" in high watercontent lenses, these lenses have had to be made thicker than manyconventional lenses. However, this approach has resulted in a decreasein oxygen transmissibility (Dk/L) which is directly related to theamount of oxygen that reaches the cornea.

At present, the primary limitation in commercial soft contact lenses istheir inability to provide adequate oxygen transmissbility to thecornea. This deficiency in the present practice may produce deleteriouseffects such as edema, corneal ulcers and related conditions. There is aclear need in the art to provide contact lenses with increased oxygenpermeability without compromising drapeability, wettability, durability,"toughness" or tear-strength, clarity and resistance to deposits ofproteins, lipids and bacteria.

Surprisingly, preformed macromonomers, graft copolymers and starpolymers of the present invention can be used to enhance thecharacteristics of hard and soft contact lenses. These preformed acrylicmacromonomers, graft copolymers and star polymers may be dissolved ordispersed in silicone acrylate monomers, wetting monomers such ashydroxyethylmethacrylate, glycerol methacrylate, polyvinyl alcohols,polyvinylpyrrolidone and methacrylic acid, among others, and/or mixturesof such monomers with alkyl acrylic esters. Compositions containingpreformed copolymers may be adapted for use in hard, flexible or softcontact lenses. It has been found that bulk polymerization of thesemixtures gives products with attractive properties including opticalclarity, suitable hardness (in the case of buttons for lathing softcontact lenses), suitable drapeability and wettability (in the case ofsoft contact lenses) and enhanced oxygen permeability.

OBJECT OF THE PRESENT INVENTION

It is an object of the present invention to provide novel polymercompositions which can be used to make soft/flexible gas permeablecontact lenses having water contents of at least about 10% by weight.

It is another object of the present invention to provide methods forimproving the oxygen permeability of compositions which can be used tomake contact lenses.

It is still a further object of the present invention to providewettable highly oxygen permeable compositions according to the presentinvention which can be used to produce soft lenses having water contentsof at least about 10% by weight.

It is yet another object of the present invention to provideoxygen-permeable, wettable, transparent copolymers which can becast-molded, molded using a spin-cast system or machined to provideimproved flexible or soft contact lenses having water contents, afterhydration of at least about 10%.

It is yet a further object of the present invention to provideprepolymerized mixtures exhibiting reduced viscosity to enhance handlingand manufacture which give rise, after polymerization, to highly oxygenpermeable compositions.

These and other objects of the present invention will be readilyapparent from the description of the present invention which is setforth in detail herein.

SUMMARY OF THE INVENTION

The present invention relates to novel compositions containingmacromonomers, graft polymers and acrylic star polymers dispersed orcopolymerized throughout a polymer matrix and contact lenses made fromthese novel compositions. The novel compositions of the presentinvention comprise novel silicone-containing acrylic compositions whichare obtained from the polymerization of preformed macromonomers, graftpolymers and/or acrylic star polymers with monomers of the polymermatrix, for example, hydrophilic esters of acrylic and/or methacrylicacid ((meth)acrylates) and/or crosslinking agents, among others agentsincluding alkyl (meth)acrylates and related (meth)acrylates, andespecially including silicone acrylate monomers, among others. Thesenovel compositions may be used for a number of purposes includingproducing medical polymers such as oxygen permeable hydrated wounddresses as well as hydrated soft contact lenses having water contacts ofat least about 10% by weight.

In certain embodiments according to the present invention, thecompositions contain pre-formed silicone-containing macromonomersincorporated into, and preferably polymerized throughout, asubstantially hydrophilic polymer matrix. Macromonomers according to thepresent invention are linear homopolymers, block polymers or randomcopolymers preferably in the form of a diblock, with a first block beingsubstantially hydrophilic and a second block being substantiallyhydrophobic and permeable. The hydrophobic, permeable block generally isderived from at least about 50% by weight of silicon acrylate monomerunits and preferably consists essentially of polymerized siliconeacrylate. Most preferably, the hydrophobic, permeable block compriseshomo-polysilicone acrylate. The macromonomers which are used in thecompositions according to the present invention preferably have at leastone polymerizable olefinic group at the end of the polymer chain.Numerous additional polymerizable groups may also be attached to thepolymer chain.

Preferably, the macromonomers are preformed block copolymers having afirst substantially hydrophilic block and a second substantiallyhydrophobic, permeable block. The first substantially hydrophilic blockpreferably is derived from at least about 25% by weight of ahydrophilic, acrylic-type monomer and the second substantiallyhydrophobic, permeable block is derived from at least about 50% byweight silicone acrylate monomers. Although not required, thesemacromonomers preferably have on average at least one polymerizablegroup, preferably an olefinic group which is preferably a terminaldouble-bond-containing organo group and is in the hydrophilic block ofthe macromonomer. The inclusion of at least one polymerizable group inthe macromonomer results in the copolymerization of the macromonomerwith the mixture of monomers which comprises the polymer matrix. Thedouble-bond-containing organo group is generally linked to the end ofthe macromonomer by means of a urethane, ester, ether, amide or relatedlinkage. In certain embodiments more than one polymerizable group islinked to the macromonomer at sites on the macromonomer which mayinclude a terminal site. The polymerizable group may be, for example, adouble bond from a methacryloxy, an acryloxy, a styrenic, an alphamethyl styrenic, an allylic, vinylic or other olefinic group.

In certain preferred embodiments, these pre-formed macromonomerscomprise a first substantially hydrophilic block which is derived fromat least about 25% by weight of at least one hydrophilic acrylic-typemonomer. Preferred hydrophilic acrylic-type monomers for use in thepresent invention include hydrophilic (meth)acrylates, and (meth)acrylicacids, for example, hydroxyethylmethacrylate (HEMA),glycerolmethacrylate (GMA), methacrylic acid and acrylic acid. Otherhydrophilic acrylic-type monomers well known in the art may also be usedin the macromonomers according to the present invention.

The hydrophobic, permeable block of the macromonomer is derived frommonomer units comprising at least about 50% by weight to at least onepolysiloxanylalkyl ester (silicone acrylate) preferably having theformula ##STR1## where D and E are selected from the group consisting ofC₁ -C₅ alkyl groups, phenyl groups, and groups of the structure ##STR2##where A is selected from the group consisting of C₁ -C₅ alkyl groups andphenyl groups; m is an integer from one to five except that m is aninteger from one to fifteen when A, D and E are C₁ alkyl groups; and nis an integer from one to three; R₂ is --H or --CH₃.

In most instances, the substantially hydrophilic block of themacromonomer comprises about 5% to about 95% by weight of saidmacromonomer and the hydrophobic, permeable block comprises about 5% toabout 95% by weight of said macromonomer and preferably the hydrophilicblock comprises no less than about 20% by weight of the macromonomer.

In additional aspects of the present invention, the novel polymerscomprise pre-formed silicone-containing acrylic star polymersincorporated into, and preferably copolymerized throughout, a polymermatrix. In certain embodiments, these preformed star polymers arecomprised of a crosslinked core derived from one or more esters ofacrylic or methacrylic acid ((meth)acrylate) monomers and a plurality oflinear copolymeric arms having an unattached free end attached to thecore. In other embodiments the core of the acrylic star polymer may be apolysiloxane core made, for example, by the polycondensation ofsubstituent alkoxysilyl groups contained in acrylic ester groups oracrylic block copolymers as taught in U.S. Pat. No. 5,036,139, issuedJul. 30, 1991.

The arms of the star polymer comprise a first substantially hydrophilicblock and a second substantially hydrophobic, permeable block. Inpreferred embodiments of the star polymers according to this aspect ofthe present invention, the hydrophobic, permeable block is nearest thecrosslinked core and the substantially hydrophilic block is furthestfrom the crosslinked core. Thus, the preferred star polymers comprise acrosslinked core to which are attached polymeric arms, the block of thearms nearest the crosslinked core comprise a hydrophobic, permeableblock and the block of the arms furthest from the crosslinked corecomprise a substantially hydrophilic block. While not being limited byway of theory, it is believed that star polymers having this preferredstructure are able to compatibilize with a hydrophilic matrix andproduce two distinct phases in the final composition: a substantiallyhydrophilic phase surrounding a separate, substantially hydrophobic,permeable phase. Preferably, prior to incorporation into the finalcompositions according to the present invention, these star polymershave at least one polymerizable group attached to the arms, mostpreferably attached to the substantially hydrophilic block of the arm.

Preferably, these star polymers comprise:

a. a crosslinked core comprising a polymer derived from a mixture ofmonomers comprising

i). 1-100% by weight of one or more monomers each having at least twopolymerizable groups, ##STR3## ii. about 0-99% by weight of one or moremonomers, each having one group, ##STR4## in which R₃ is the same ordifferent and is H, CH₃, CH₃ CH₂, CN, or COR' and Z is 0, or NR', R' isC1-C4 alkyl and

b) attached to said core, at least one polymeric arm, each armcomprising a substantially hydrophilic block and a substantiallyhydrophobic, permeable block, said hydrophilic block comprising at leastabout 25% by weight of a hydrophilic acrylictype monomer and saidhydrophobic, permeable block comprising at least about 50% by weight ofat least one one or more polysiloxanylalkyl ester.

In preferred embodiments according to the present invention, thepolysiloxanylalkyl ester has the formula: ##STR5## where A is selectedfrom the class consisting of C1-C5 alkyl groups, phenyl groups, and Ggroups; G is a group of the structure: ##STR6## where D and E areselected from the class consisting of C₁₋₅ alkyl groups, phenyl groupsand G groups; R₂ is selected from the group of hydrogen and methyl; m isan integer from one to five, except that m is an integer from one tofifteen when A, D and E are C₁ alkyl groups and n is an integer from oneto three; and the unattached ends of said arms have a terminal organogroup containing a copolymerizable carbon-carbon double bond.

Preferably, in the preformed star polymers, at least 5 of the arms arepresent, and most preferably at least 5 of the arms have theirunattached ends, preferably, the substantially hydrophilic block of thearm, terminated with an organo group containing a polymerizablecarbon-carbon double (olefinic) bond. In certain cases, more than onedouble bond may be included on the arms of the star polymers. Suchdouble bonds permit the preformed star polymer to copolymerize withother monomers to form the novel copolymers of the present invention.Other preferred star polymers for use in the present invention maycontain between one and five polymerizable carbon-carbon double bondspreferably distributed in the hydrophilic block of the arm.

The copolymerization of the star polymer with the matrix of compositionsaccording to the present invention results in a novel polymer withimproved resistance to extraction and greater reinforcement ofproperties, such as toughness and machineability, in the polymercombination. In soft contact lens copolymers, enhanced oxygenpermeability in addition to increased toughness of the final hydratedcontact lens results from the inclusion of the pre-formed macromonomers,graft copolymers and/or star copolymers in copolymers of the presentinvention.

Compositions of the present invention comprise a polymer formed by thebulk polymerization of preformed macromonomers, graft copolymers and/orstar polymers as described above in combination with a substantiallyhydrophilic matrix comprising a mixture of monomers, said monomermixture comprising at least 25% by weight of at least one hydrophilicmonomer. In certain preferred embodiments according to the presentinvention, the monomer mixture comprises at least 25% by weight of atleast one hydrophilic monomer and at least one additional monomerselected from the group consisting of esters of alpha, beta unsaturatedacids such as acrylic and methacrylic acid, among others, crosslinkingagents, and mixtures thereof.

In other particularly preferred embodiments, polysiloxanylalkyl estersof alpha, beta unsaturated acids such as acrylic and methacrylic acid,as well as fluorine acrylates as described hereinbelow may also be addedto the matrix. It has now been surprisingly and unexpectedly beendiscovered that the inclusion in the monomer mixture of at least onepolysiloxanylalkylester of an alpha, beta unsaturated acid (siliconeacrylate) in an amount of at least about 5% by weight of the finalcomposition leads to compositions having unexpectedly enhanced oxygenpermeability. In addition, the inclusion in the mixture of monomers ofat least about 5% by weight silicone acrylate in the final compositionresults in a prepolymerized mixture which is substantially lower inviscosity than compositions which do not contain monomeric siliconeacrylate. This is an unexpected result.

While not being limited by way of theory, it is believed that thesilicone acrylate in the monomer mixtures of the compositions accordingto the present invention partitions into a hydrophobic, permeable phasecreated by the substantially hydrophobic, permeable block of thepreformed silicone-containing acrylic copolymer when the copolymer isdissolved or dispersed in the mixture of monomers. It is believed thatthe inclusion of at least about 5% by weight of at least one siliconeacrylate in the compositions according to the present invention createsa more workable mixture having lower viscosity and after polymerization,a composition having substantially enhanced oxygen permeability relativeto those compositions which do not include silicone acrylate. Thus, thepresent invention identifies a means by which the oxygen permeability ofcompositions containing preformed silicone-containing acrylic copolymersmay be made more workable and have substantially enhanced oxygenpermeability. This is an unexpected result.

Preferred polysiloxanylalkylesters of alpha, beta unsaturated esters(silicone acrylates) for inclusion in the monomer mixture according tothe present invention have the formula: ##STR7## where A is selectedfrom the class consisting of C1-C5 alkyl groups, phenyl groups, and Ggroups; G is a group of the structure: ##STR8## where D and E areselected from the class consisting of C₁ -C₅ alkyl groups, phenyl groupsand G groups; R₂ is selected from the group of hydrogen and methyl; m isan integer from one to five, except that m is an integer from one tofifteen when A, D and E are C₁ alkyl groups and n is an integer from oneto three; and the unattached ends of said arms have a terminal organogroup containing a copolymerizable carbon-carbon double bond.Preferably, m is an integer from one to seven when A, D and E are C₁alkyl groups. A particularly preferred silicone acrylate for inclusionin the mixture of monomers isTris(trimethylsiloxy)-3-methacryloxypropylsilane.

The silicone acrylate is included in the mixture of monomers accordingto the present invention in any amount of at least about 5% by weight ofthe composition, but preferably, the amount of silicone acrylate rangesfrom about 10% to about 70% by weight and most preferably ranges fromabout 10% to about 45% by weight. In these most preferred compositions,the amount of preformed silicone-containing acrylic copolymer rangesfrom about 20% to about 50% by weight.

While the ratio of preformed silicone-containing copolymer to siliconeacrylate in the prepolymerized composition is generally not critical,for purposes of producing highly wettable, highly oxygen permeable softcontact lens materials, the amount of silicone acrylate included in themixture of monomers (by weight of the total weight of the composition)in compositions according to the present invention is preferably lessthan the amount by weight of preformed silicone-containing acryliccopolymer used.

By including at least about 5% by weight of a silicone acrylate in themixture of monomers in compositions according to the present invention,it has surprisingly been discovered that the amount of preformedsilicone-containing acrylic copolymer included in the prepolymerizedcomposition easily may be increased. The inclusion of silicone acrylatein effective amounts of at least about 5% by weight of the finalcomposition substantially reduces the viscosity of the prepolymerizedmixture making it significantly easier to handle and manufacture at thesame time that oxygen permeability significantly increases in the finalcomposition. In many instances, a prepolymerized mixture which isdifficult to handle and manipulate because the viscosity attains thecharacteristics approaching a gel which, in turn, limits the speed withwhich the material may be manipulated or delivered and which may trapgaseous bubbles, will become significantly easier to handle and work bythe inclusion of monomeric silicone acrylate.

The weight ratio of the macromonomer, graft copolymer star polymer andother monomers may be readily varied to produce the compositionsaccording to the present invention. In general, the macromonomer, graftcopolymer or star polymer comprises about 10% to as much as 98% or moreby weight of the final product and the substantially hydrophilic matrixcomprises about 2% to about 90% by weight of the compositions. Incertain cases, it is possible to provide final compositions which aremade exclusively (100% by weight) from the preformed silicone-containingacrylic copolymer. After hydration, compositions according to thepresent invention comprise at least about 10% by weight water.

In compositions according to the present invention which includesilicone acrylic in the mixture of monomers, it is generally preferredthat the amount of preformed silicone-containing acrylic copolymershould be no less than about the amount of silicone acrylate included inthe mixture of monomers.

The compositions according to the present invention find utility in anumber of diverse applications including contact lenses, wounddressings, release coatings, ocular membranes, intraocular implants,sizing agents, electronics adhesives, gas and liquid separationmembranes, prostheses and etching resists, among others, especiallywhere hydrogels may be used. The compositions according to the presentinvention find particular utility in contact lenses and as wounddressings.

The compositions according to the present invention may be manufacturedinto contact lenses using traditional methods well known in theindustry, including lathing polymer buttons and cast-molding completedlenses. In addition, the compositions according to the present inventionwhich are useful for making soft contact lenses exhibit favorableviscosities for use in spin-casting completed lenses using methodswell-known in the art.

SUMMARY OF THE FIGURES

FIGS. 1A, 1B and 1C sets forth the names and chemical structures ofnumerous exemplary silicone acrylates that may be used in the presentinvention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

For purposes of clarity, throughout the discussion of the presentinvention, the following definitions will be used:

The term "copolymer" is used throughout the specification to describe apolymer that results from the polymerization of at least two differentmonomers. The term copolymer includes polymers of the present inventionobtained by the bulk polymerization of monomers and the macromonomers,graft copolymers and/or star polymers of the present invention.

The term "monomer" is used throughout the specification to describechemical compounds containing at least one polymerizable double bondthat are the non-preformed building blocks of the preformed polymers andcompositions according to the present invention. Monomers includesilicone acrylates, esters of alpha, beta-unsaturated acids includingesters of acrylic and methacrylic acid ((meth)acrylates) such as methylmethacrylate, among others, fluoroacrylates, hydrophilic ("wetting")monomers, including certain acrylonitrile monomers, hydrophilicacrylic-type monomers and crosslinking monomers, among others.

The term "macromonomer" is used throughout the specification to describepreformed linear silicone-containing acrylic polymers which may be usedto produce hydrated oxygen permeable compositions. The macromonomersaccording to the present invention preferably comprise a firstsubstantially hydrophilic block derived from at least about 25% byweight of at least one hydrophilic acrylic-type monomer and a secondsubstantially hydrophobic, permeable block derived from at least about50% by weight of at least one polysiloxanylalkyl ester of an alpha, betaunsaturated ester. Preferably, the hydrophilic block of themacromonomers comprises substantially more than 25% by weight ofhydrophilic acrylic-type monomer units and in certain embodiments maycomprise up to 100% by weight hydrophilic acrylic-type monomer units. Incertain embodiments according to the present invention, however, thehydrophobic, permeable block may comprise as much as 100% by weight ofthe macromonomer. The amount of hydrophilic monomer included in thehydrophilic block and the rest of the macromonomer according to thepresent invention is that amount which is effective to produce, incombination with a matrix, a composition comprising at least about 10%by weight water after hydration. Macromonomers according to the presentinvention preferably have a polymerizable group at one end of thepolymer chain and are used in the contact lens polymers of the presentinvention. In preferred embodiments, the polymerizable group of themacromonomer may be a double bond from a methacryloxy, an acryloxy, astyrenic, an alpha methyl styrenic, an allylic, a vinylic or otherolefinic group. In certain embodiments it may be advantageous for themacromonomer to contain more than one polymerizable group, mostpreferably with at least one of such groups at the end of the polymerchain (and generally in the hydrophilic block). It is also possible,although less preferable, to utilize a macromonomer containing anabsence of polymerizable groups which is simply dispersed throughout thepolymer matrix of the copolymers of the present invention. In the caseof the use of macromonomers in soft, hydrated contact lenses, thisapproach may be less preferred because of the inability of the matrix ina hydrated soft contact lens to provide adequate structural integrityfor the dispersed macromonomers. The terms "region" and "block" whendescribing macromonomers and other preformed polymers according to thepresent invention are synonymous and may be used interchangeably.

The term "star polymer" or "star copolymer" is used throughout thespecification to describe high molecular weight silicone-containingpolymers for use in the present invention that generally have amultitude of linear, acrylic arms radiating out from a central core. Thearms are linear polymers having at least one substantially hydrophilicblock preferably derived from at least about 20-25% by weight ofhydrophilic acrylic-type monomers and at least one substantiallyhydrophobic, permeable block derived from at least about 50% by weightof at least one polysiloxanylalkyl ester of an alpha, beta, unsaturatedester (silicone acrylate). The amount of hydrophilic monomer included inthe hydrophilic block and the rest of the star polymer according to thepresent invention is that amount which is effective to produce, incombination with a matrix, a composition comprising at least about 10%by weight water after hydration. Preferably, the arms of the starpolymer contain one substantially hydrophilic block and onesubstantially hydrophobic, permeable block. In general, thesubstantially hydrophilic block of the arms of the star polymercomprises about 5% to about 95% by weight of said arm and thesubstantially hydrophobic, permeable block comprises about 5% to about95% by weight of said arm. In certain embodiments according to thepresent invention, however, the hydrophobic, permeable block maycomprise as much as 100% by weight of said arm. The star polymers mayhave functional groups such as polymerizable double bonds, hydroxylgroups and carboxyl groups located at the end of the arms or distributedalong the chain. In general, the cores are highly crosslinked segmentsof difunctional acrylates, copolymers of monofunctional and difunctionalacrylates. In addition, the core of the star polymer may be acrosslinked polysiloxy core derived from a multifunctional crosslinkablesilicone-containing group, such as a polyalkoxysilyl group, asdescribed, for example in U.S. Pat. No. 5,036,139, which is incorporatedby reference herein. The star polymers of the present invention may bedispersed or preferably copolymerized throughout the matrix ofcopolymers of the present invention.

The term "graft copolymer" is used throughout the specification todescribe "branched" or "comb" copolymers which are similar to themacromonomers and star polymers according to the present invention.Graft copolymers according to the present invention are high molecularweight silicone-containing polymers for use in the present inventionthat generally have a number of linear, polymeric arms grafted onto apolymeric backbone. Graft copolymers according to the present inventionpreferably comprise at least one substantially hydrophilic block orregion and one substantially hydrophobic, permeable block or region.Preferably, the backbone of the graft copolymer is comprised of asubstantially hydrophilic block (generally derived from at least about20-25% by weight of hydrophilic acrylic-type monomers) to which a numberof arms is bound at varying points along the backbone. The amount ofhydrophilic monomer included in the hydrophilic block and the rest ofthe graft copolymer according to the present invention is that amountwhich is effective to produce, in combination with a matrix, acomposition comprising at least about 10% by weight water afterhydration. In certain instances, the backbone may instead comprise asubstantially hydrophobic, permeable block (even up to 100% by weight ofthe backbone). The arms of the graft copolymers are generally linearpolymers which may be random, homo or block copolymers. The arms arepreferably comprised of at least one substantially hydrophobic,permeable block and most preferably, the arms are homopolymers ofmonomeric units of polysiloxanylalkyl esters of alpha, beta unsaturatedacids. The arms may also preferably comprise a first hydrophilic blockderived from at least about 25% by weight of a hydrophilic acrylic-typemonomer and at least one substantially hydrophobic, permeable blockderived from at least about 50% by weight of a polysiloxanylakyl esterof an alpha, beta, unsaturated acid. In general, the substantiallyhydrophilic block of the graft copolymer comprises about 5% to about 95%by weight of said arm and the substantially hydrophobic, permeable blockcomprises about 5% to about 95% by weight of said arm. In certainembodiments according to the present invention, however, thehydrophobic, permeable block may comprise as much as 100% by weight ofthe arm(s). The graft copolymers may have functional groups such aspolymerizable double bonds, hydroxyl and carboxyl groups located at theend of the arms or distributed along the chain. The graft copolymers ofthe present invention may be dispersed or preferably copolymerizedthroughout the matrix of copolymers of the present invention.

The terms "preformed silicone-containing acrylic copolymer", "preformedsilicone-containing copolymer" and "preformed copolymer" are usedthroughout the specification to describe the macromonomers, graftpolymers and star polymers used in the compositions of the presentinvention. These macromonomers, graft copolymers and star polymers arederived from esters of alpha, beta unsaturated acids such as hydrophilicmonomers, for example hydroxyethyl methacrylate, glycerol methacrylate,polymerizable acids, for example, methacrylic and acrylic acid,non-hydrophilic esters of alpha, beta unsaturated acids such as methylmethacrylate, ethyl methacrylate, propyl methacrylate and butylmethacrylate, among others, silicone acrylates such as TRIS, among othermonomers including other alpha, beta unsaturated monomers havingactivated polymerizable double bonds such as acrylonitriles, amongothers. These preformed copolymers preferably are derived from at leastabout 10% by weight silicone acrylates. In addition, these preformedcopolymers are derived from an amount of a hydrophilic monomereffective, in combination with a surrounding substantially hydrophilicmatrix, to produce a hydrated composition having a water content of atleast about 10% by weight. The amount of hydrophilic acrylic-typemonomer included in the preformed copolymer will range from about 0% toabout 90 % by weight of the preformed copolymer.

The term "matrix" is used throughout the specification to describe thatpart of the composition that generally results from the randompolymerization of the monomer mixture ("mixture of monomers") andproduces a substantially hydrophilic phase. The mixture of monomerscontains at least one hydrophilic monomer in an amount effective toproduce, after polymerization with the preformed silicone-containingacrylic copolymers followed by hydration, a composition which containsat least about 10% by weight water. In general, the mixture of monomersutilized in the present invention ranges from about 5% to about 90% (incertain cases, 0% to about 90%) by weight of the compositions. Inpreferred embodiments according to the present invention the mixture ofmonomers (which includes monomeric silicone acrylate) comprises at leastabout 10% by weight of the final compositions. In addition to theinclusion of hydrophilic monomers, the mixture of monomers may alsoinclude a monomer selected from the group consisting of siliconeacrylates, esters of alpha, beta-unsaturated acids, crosslinkingmonomers, and mixtures thereof, among others. Of course, the amount andtype of monomers other than hydrophilic monomers which may be used inthe matrix will vary according to the amount and type of hydrophilicmonomer utilized in the preformed silicone-containing acrylic copolymerused and the amount and type of such copolymer included in the finalcomposition.

It has now been unexpectedly discovered that the inclusion of at leastabout 5% by weight of a silicone acrylate (by weight of the finalcomposition) in the monomer mixture will produce a prepolymerizedmixture with reduced viscosity and upon polymerization, a materialhaving significantly increased permeability yet having the samefavorable characteristics of traditional soft contact lens materials,especially including the substantial wettability of the surface of thematerial. While not being limited by way of theory, it is believed thatthe monomeric silicon acrylate partitions into and polymerizes withinthe substantially hydrophobic permeable phase formed by the preformedcopolymers dispersed or dissolved in the mixture of monomers.

The weight ratios of the various individual components included in thecompositions according to the present invention may also vary, dependingupon the final water content desired. One of ordinary skill in the artwill recognize that the amount and type of individual monomers andpreformed silicone-containing copolymers utilized in the presentinvention may be varied over a wide range. The matrix monomers aredistinct from the macromonomers, graft copolymers or star polymers whichare also incorporated into the compositions according to the presentinvention. The compositions of the present invention comprise the matrixand graft copolymer, macromonomer and/or star polymer dispersed orpreferably copolymerized throughout the matrix.

The term "difunctional acrylate" is used throughout the specification todescribe a chemical compound having at least two acrylatefunctionalities. In addition to being monomers, crosslinking monomersfor use in the present invention are difunctional acrylates.

The terms "silicone acrylate(s)" or "silicone monomers" are usedthroughout the specification to describe polysiloxanylalkyl esters ofalpha, beta unsaturated acids including acrylic and methacrylic acidswhich are included in macromonomers, great copolymers, star polymers andthe matrix of the copolymers of the present invention.

The term "(meth)acrylate(s)" is used throughout the specification todescribe esters of acrylic and methacrylic acid.

The term "non-silicone ester(s)" is used throughout the specification todescribe esters of alpha, beta-unsaturated acids including esters ofacrylic and methacrylic acid ((meth)acrylates) which are included in themacromonomers, star polymers and polymer matrix of the copolymers of thepresent invention which do not include silicone. It is understood thatthe term ester of alpha, beta-unsaturated acid is exclusive of siliconacrylates and is synonymous with the term non-silicone ester. The termnon-silicone esters includes non-hydrogel (non-hydrophilic) esters suchas alkyl esters of (meth)acrylic acid, for example, methyl methacrylate,ethyl methacrylate, propyl methacrylate, butyl methacrylate and relatedesters of acrylic and methacrylic acid which do not form hydrogels whenexposed to water. The term non-silicone esters also includes hydrophilicmonomers such as hydroxyethyl methacrylate, glycerol methacrylate,methacrylic and acrylic acid, which may be included in the polymermatrix of soft contact lenses because of their ability to producehydrogels after hydration.

The term "fluoro acrylate(s)" is used throughout the specification todescribe fluorine containing esters of alpha, beta unsaturated acidsincluding acrylic and methacrylic acid that may be included in thecopolymers, including the macromonomer, graft copolymer, star polymersand the polymer matrix to provide structure integrity and, in certaininstances, enhanced oxygen permeability.

The term "hydrophilic acrylic-type monomer" is used throughout thespecification to describe hydrophilic monomers which may be incorporatedinto macromonomers, graft copolymers and star polymers according to thepresent invention. The term hydrophilic acrylic-type monomer includeshydrophilic non-silicone esters of alpha, beta unsaturated acids such asacrylic and methacrylic acid, for example, hydroxyethyl methacrylate andglycerol methacrylate as well as alpha, beta unsaturated acids,especially including methacrylic and acrylic acid. In addition,hydrophilic monomers containing an activated olefinic group (alpha, betaunsaturated monomers) similar to (meth)acrylates such as hydrophilicacrylonitriles and acrylamides, among other monomers, are also includedunder this term.

The term "hydrophilic monomer" is used throughout the specification todescribe monomers having an affinity for water which may be incorporatedinto the polymer matrix of copolymers according to the present inventionto provide a hydrophilic component to the matrix. The term hydrophilicmonomer includes hydrophilic (hydrogel) non-silicone esters of acrylicand methacrylic acid such as hydroxyethyl methacrylate (HEMA), glycerolmethacrylate and methacrylic acid (hydrophilic acrylic-type monomers) aswell as other wetting monomers such as methacrylic acid and N-vinylpyrrolidone, among numerous others.

The term "substantially hydrophilic" is used throughout thespecification to describe the monomer matrix and hydrophilic blocks ofthe macromonomers, graft copolymers and star polymers according to thepresent invention. The term substantially hydrophilic, is used todescribe a matrix or block which has a preference or affinity for ahydrophilic chemical environment relative to a hydrophobic environment.These substantially hydrophilic blocks or matrices generally comprise atleast about 20-25% by weight of a hydrophilic acrylic-type monomer incombination with other acrylic-type monomers including alkyl esters ofalpha, beta unsaturated acids and other monomers such as fluoroacrylates and silicone acrylates which are utilized in weight ratioswhich will maintain the substantially hydrophilic character of the blockor matrix. These blocks may be random, block or homo polymers.

The term "substantially hydrophobic, permeable" is used to describeblocks of the preformed silicone-containing copolymers which have anaffinity for hydrophobic chemical environments rather than hydrophilicblocks. Moreover, these blocks are substantially more permeable thanpolymethylmethacrylate. Substantially hydrophobic, permeable blocksgenerally comprise at least about 50% by weight of a silicone acrylatein combination with other acrylic-type monomers. These blocks may berandom, block or homo polymers. Most preferably, this block consistsessentially of homo (100%) silicone acrylate.

The term "substantially wettable" is used to describe compositionsaccording to the present invention which have been hydrated and whichexhibit a wettable surface. A substantially wettable surface is asurface which exhibits a substantial absence of "dry" or non-wettablespots after the surface is exposed to water.

Compositions according to the present invention comprise a polymercomprising a macromonomer, graft copolymer and/or a star polymerpreferably copolymerized throughout a polymer matrix derived from amixture of monomers which includes at least about 5% by weight (of thefinal composition) of a silicone acrylate, said mixture of monomershaving sufficient hydrophilic character in the final composition incombination with the macromonomer, graft copolymer or star polymer toprovide a composition comprising at least about 10% by weight waterafter hydration. In the final composition, the polymer matrix maysubstantially comprise one or more hydrophilic monomers, or in certaininstances, at least one additional monomer selected from the groupconsisting of non-hydrophilic esters of alpha, beta-unsaturated acids,such as methyl methacrylate, ethyl methacrylate, propyl methacrylate,butyl and iso-butyl methacrylate, crosslinking monomers and mixturesthereof.

In certain embodiments, the mixture of monomers in the prepolymerizedcompositions includes at least one additional monomer such as a siliconeacrylate, fluoroacrylate and mixtures thereof, among others. Inparticularly preferred embodiments, a silicone acrylate is included inthe mixture of monomers in an amount of at least about 5% by weight ofsaid composition.

In synthesizing preformed silicone-containing acrylic copolymers(macromonomers, graft copolymers and star polymers) of the presentinvention, generally at least about 20% and preferably at least about25% by weight hydrophilic acrylic-type monomers are used in thesubstantially hydrophilic block. Exemplary hydrophilic acrylic-typemonomers for use in this aspect of the present invention includehydroxyethyl methacrylate, glycerol methacrylate, methacrylic andacrylic acid, among others. Virtually any hydrophilic acrylic-typemonomer may be used in this aspect of the present invention. In general,the substantially hydrophilic block of the preformed silicone-containingacrylic copolymers comprises about 0% to about 95% by weight of saidpreformed copolymer (generally, at least about 2% by weight within thisrange and preferably about 5% to about 95% by weight within this range),whereas the substantially hydrophobic, permeable block comprises atleast about 5% by weight of the preformed silicone-containing acryliccopolymer and preferably at least about 20% to about 90% by weight ofsaid copolymer.

The substantially hydrophilic block of the preformed acrylic copolymermay comprise, in addition to the hydrophilic acrylic-type monomer,amounts of a non-hydrophilic alpha, beta unsaturated ester includingcertain amounts of silicone and fluorine acrylates. Preferably, estersof acrylic and methacrylic acid, are used. Most preferably, methylmethacrylate is used because of its relative wettability and itsability, even at relatively high weight percentages, to avoidsignificantly diminishing the hydrophilic character of the hydrophilicblock. These non-hydrophilic alpha, beta unsaturated esters may also beused in the hydrophobic, permeable block of the preformed acryliccopolymers.

The amount of non-hydrophilic monomers chosen for use in the preformedcopolymers may vary but will be chosen so as not to significantly impactthe overall chemical characteristics (hydrophilic or hydrophobic,permeable) desired. It is noted that when more hydrophobic esters arechosen, the amount of ester which may be added to the hydrophilic blockis relatively small and the amount of ester which may be added to thehydrophobic, permeable block may be relatively large (although there maybe a significant decrease in permeability relative to a homo block ofpolysilicone acrylate).

Representative esters of acrylic and methacrylic acid which are used inthe present invention may include, for example, butyl methacrylate,sorbyl acrylate and methacrylate; 2-(dimethylamino)ethyl methacrylate,2- (dimethylamino)ethyl acrylate; 3,3-dimethoxypropyl acrylate; 3-methacryloxypropyl acrylate; 2-acetoxyethyl methacrylate; p-tolylmethacrylate; methylene malononitrile; ethyl 2-cyanoacrylate;N,N-dimethyl acrylamide; 4- fluorophenyl acrylate; 2-methacryloxyethylacrylate and linoleate; propyl vinyl ketone ethyl 2-chloroacrylate;glycidyl methacrylate; 3-methoxypropyl methacrylate;2[(1-propenyl)oxylethyl methacrylate and acrylate; phenyl acrylate;2-(trimethyloloxy)ethyl methacrylate; allyl acrylate and methacrylate.Preferred monomers of this group include methyl methacrylate, glycidylmethacrylate; sorbyl methacrylate; ethyl acrylate, butyl acrylate;sorbyl acrylate; 2-(trimethylsiloxy)ethyl methacrylate;2-methacryloxyethyl acrylate, 2-acetoxyethyl methacrylate; and2-(dimethylamino)ethyl methacrylate, among others, including mixtures ofthese esters.

In addition to the above, esters of itaconic acid, maleic acid andfumaric acid and related polymerizable esters of alpha, beta-unsaturatedacids may also be used. One of ordinary skill in the polymer arts willrecognize that the particular ester chosen for use in the macromonomers,the graft copolymers, the star polymers or for the matrix of the presentinvention may vary depending upon the type of characteristics desiredfor the individual components as well as the final copolymer. One ofordinary skill in the art will also recognize that the choice of theester will also vary according to the compatibility of the macromonomer,graft copolymer or star polymer with the polymer matrix.

For synthesizing macromonomers, graft copolymers and star polymersaccording to the present invention, the amount of the ester of alpha,beta unsaturated acid (non-silicone esters) included will vary over alarge range as a function of the rigidity, oxygen permeability and finalwater content desired as well as the composition of the mixture ofmonomers and the compatability of the macromonomers, graft copolymersand/or star polymers within the matrix, and the total amount of siliconeacrylate included in the preformed copolymers or the mixture ofmonomers. Esters of acrylic and methacrylic acid, especially includingmethyl methacrylate, among others, are preferred.

In general, an ester of methacrylic or acrylic acid is included in thepreformed acrylic copolymer in an amount ranging from about 1% by weightup to about 75% by weight, or higher. In the case of macromonomers to beused in mid to high water content soft contact lenses, non-hydrophilicacrylic monomers are included in a preferred range of about 1% to about45% by weight and a most preferred range of about 1% to about 10% byweight. Although in certain cases the amount of such ester included inthe preformed acrylic copolymer may be above or below the broadestrange, practical problems related to the solubility, manufacturabilityand water content of the contact lenses may occur.

In the compositions of the present invention which include at least 5%by weight (of the final composition) of a silicone acrylate in themixture of monomers, the amount of hydrophilic monomer included in themixture of monomers will vary as a function of the amount of siliconeacrylate included. In general, the amount of hydrophilic monomerincluded in the mixture of monomers usually ranges from at least about20% and approaches 95%, preferably at least about 25% of the weight ofthe mixture of monomers. The hydrophilic matrix portion of the finalcompositions (which typically excludes the substantial majority ofsilicone acrylate) ranges from about 0% to about 90% by weight,preferably at least about 5% to about 70% and most preferably at leastabout 10% to about 50% by weight of the composition.

It is noted that the final polymerized compositions according to thepresent invention generally comprise a substantially hydrophilic phaseand a substantially hydrophobic phase with the substantially hydrophilicmonomers of the mixture of monomers generally being found in thesubstantially hydrophilic phase of the final compositions and thehydrophobic monomers and in particular, the silicone acrylates beingfound in the substantially hydrophobic phase. It is further noted thatthe term matrix generally refers to substantially hydrophilic phase madefrom the polymerization of a mixture of hydrophilic monomers whichpreferably surrounds the substantially hydrophobic phase.

The preformed silicone-containing acrylic copolymers of the presentinvention also contain a silicone acrylate monomer in the hydrophobic,permeable block of the copolymer in quantities sufficient to providesignificantly enhanced oxygen permeability relative to PMMA. In general,the silicone acrylate monomer in the hydrophobic, permeable blockcomprises at least about 50% by weight of the block and more preferably,at least about 80% by weight of the block. In certain particularlypreferred embodiments for use in highly oxygen permeable soft contactlenses, the amount of silicone acrylate approaches 100% by weight of thehydrophobic, permeable block of the preformed copolymer.

Representative silicone acrylates which are employed for use in thepresent invention include, for example, phenyltetraethyldisiloxanylethermethacrylate, triphenyldimethyldisiloxanylmethyl acrylate,isobutylhexamethyltrisiloxanylmethyl methacrylate,methyldi(trimethylsiloxy)-methacryloxymethylsilane,n-propyloctamethyltetrasiloxanylpropylmethacrylate,pentamethyldi(trimethylsiloxy)-acryloxymethylsilane,t-butyltetramethyldisiloxanylethylacrylate,n-pentylhexamethyltrisiloxanylmethylmethacrylate,tri-i-propyltetramethyltrisiloxanylethyl acrylate,pentamethyldisiloxanylmethyl methacrylate, heptamethyltrisiloxanylethylacrylate, tris(trimethylsiloxy-3-methacryloxypropylsilane andphenyltetramethyldisiloxanylethyl acrylate, among others, includingmixtures of these silicone acrylates. Chemical structures of theabove-named silicone acrylate monomers are presented in FIG. 1. Othersilicone acrylates for use in the present invention include thealkoxysilicone acrylates, such as those described in U.S. Pat. No.4,861,840 to Lim, et al., relevant portions of which are incorporated byreference herein, as well as other numerous silicone acrylates which arereadily available in the art.

Particularly preferred silicone acrylates for use in the preformedacrylic copolymers and in the mixture of monomers according to thepresent invention includeTRIS(trimethylsiloxy)-3-methacryloxypropylsilane (TRIS). In the mixtureof monomers, the use of3-[3-methacryloxypropyl-1,3,3-tris(trimethylsiloxy)]-1-methyl-1-vinyldisiloxane("VIN"-available in a mixture containing silicone acrylates includingTRIS as PSX 374™ from Petrarch Systems, Inc., Pennsylvania, U.S.A.) mayalso be advantageous. In the preformed copolymers of the presentinvention, the amount of silicone acrylate used ranges from about 10% toabout 100% by weight, preferably about 20% to about 85% by weight andmost preferably about 30% to about 80% by weight. In the finalcompositions according to the present invention, the total amount ofunits of silicone acrylate (which includes units derived from monomericsilicone acrylate from the mixture of monomers as well as siliconeacrylate units in the preformed copolymers) generally ranges from about5% to about 85% by weight. More preferably, the total amount of siliconeacrylate comprises about 10% to about 60% by weight of said compositionand most preferably, about 15% to about 50% by weight of saidcomposition, at least 5% by weight of which is derived from monomericsilicone acrylate from the mixture of monomers. In the mixture ofmonomers, the amount of silicone acrylate comprises at least about 5% byweight of the final composition.

In the soft contact lens aspect of the present invention, preformedsilicone-containing acrylic copolymers that have improved the balance ofthe properties of soft lenses are macromonomer, graft copolymers andstar polymers that have a block consisting essentially of monomericunits of one or more silicon acrylates (approaching 100% siliconeacrylate) and a block containing at least a substantial proportion ofmonomeric units of hydrophilic acrylic-type monomers, i.e., enoughhydrophilic monomer to provide sufficient overall hydrophilic characterto that portion of the preformed copolymer to enhance the solubility ofthe pre-formed copolymer in the polymer matrix monomer mixture. Ingeneral, the amount of hydrophilic acrylic-type monomer is at leastabout 20% by weight of the substantially hydrophilic block. Preferably,the amount of hydrophilic monomer ranges from about 50% to about 100%and most preferably ranges from about 85% to about 97+% by weight of thehydrophilic block.

In mid to high water content soft contact lenses, preferred preformedcopolymers are made with a pure block of silicone acrylate and ahydrophilic block containing a random copolymer of HEMA and siliconacrylate or HEMA and methyl methacrylate which has characteristics ofsolubility in the mixture of monomers. Most preferably, thesubstantially hydrophilic block comprises a random copolymer of HEMA andmethyl methacrylate, because of the neutral surface characteristics suchcopolymers are believed to impart to the final compositions. Thefollowing provides a range of compositions that have exhibitedacceptable compatability with hydrophilic monomers and have beenincorporated into soft contact lenses:

    ______________________________________                                        Permeable                                                                     Block (Weight Percent)//Hydrophilic Block (Weight Percent)                    TRIS            HEMA/    TRIS/   MMA                                          ______________________________________                                        80              20        0       0                                           75              18        7       0                                           59              30       11       0                                           67              17       16       0                                           33              42       24       0                                           51              19       30       0                                           61.5             7.5      0      31                                           63              30        7       0                                           68              29        0       3                                           ______________________________________                                    

In general, the size of the hydrophilic block of the preformed acryliccopolymer in this soft contact lens aspect of the present inventionranges from about 10% to about 90% by weight of the total weight of thecopolymer. Preferably the hydrophilic block ranges from about 20% toabout 70% by weight of the copolymer and most preferably about 20% toabout 50% by weight of the preformed copolymer. In the presentinvention, it has been found that a hydrophilic block comprising about20% to about 50% by weight of the preformed acrylic copolymer canaccommodate significant quantities of silicone acrylate in the mixtureof monomers and maintain other favorable characteristics of soft contactlens materials. The composition of the hydrophilic block generallyranges from about 20% to about 100% by weight of a hydrophilicacrylic-type monomer, preferably a hydrophilic ester of acrylic acid ormethacrylic acid and 0% to about 80% by weight of a non-silicone ester,silicone acrylate (preferably significantly less than 505 by weightsilicone acrylate) or other monomer, most preferably methylmethacrylate. Preferably, the hydrophilic block of the pre-formedacrylic copolymer ranges from about 50% to about 97+% by weight of ahydrophilic acrylic-type monomer.

The size of the substantially hydrophobic, permeable block in thepreformed silicone-containing acrylic copolymer in the soft contact lensaspect of the present invention ranges from about 10% to about 100%(generally less than about 90% within this range) by weight of thepreformed acrylic copolymer with 30% to about 80% being preferred. Ingeneral, this block is derived from about 50% to about 100% by weight ofa silicone acrylate with about 80% to about 100% by weight siliconeacrylate being preferred. These amounts of silicone acrylate in thehydrophobic block provide a favorable environment to accommodate weightratios of silicone acrylate in the mixture of monomers which haveproduced favorable characteristics in the final composition. Weightratios of silicone acrylate in the hydrophobic block below this rangemay also be used depending upon the monomers used in the mixture ofmonomers including the amount and type of silicone acrylate chosen.Other traditional hydrophilic and non-hydrophilic acrylic-type estersmay be copolymerized with the silicone acrylates in the permeable blockof the preformed copolymer with methyl methacrylate,hydroxyethylmethacrylate and methacrylic acid being preferred.

The preformed acrylic copolymer for use in the soft contact lens aspectof the present invention may be a linear polymer, a graft copolymer or astar polymer each of which contains at least two distinct blocks orregions (one hydrophobic and permeable, one hydrophilic in character).Reactive double bonds may be attached at the ends of either the linearor star polymer chains or they may be distributed along the chain(s).Preferably, the reactive double bonds are distributed in the hydrophilicblock of the preformed acrylic copolymer. The presence of the doublebond(s) is not essential, although it is preferred. In the case ofmacromonomers, most preferably, at least on average, about 1 to 3 doublebonds are preferred with a most preferred number of double bonds rangingfrom about 1.5 to about 2 double bonds per copolymer. It is noteworthythat the double bonds which are included in the preformed copolymersaccording to the present invention represents an "average" number ofbonds, and will range within a given population of copolymers from about"0" to significantly higher than the average. Gaussian distribution ofdouble bonds applies to the population of preformed copolymers.

The amount of preformed acrylic copolymer used in the soft lenscomposition generally ranges from about 10% to about 95% by weight ofthe final composition, preferably about 15% to about 60% by weightacrylic copolymer, with about 20% to about 45% being most preferred.When about 5% by weight monomeric silicone acrylate is included in themixture of monomers, the amount of preformed copolymer generally rangesfrom about 10% to about 95% by weight of the final composition.

In certain embodiments fluorine containing esters ("fluoro esters") ofalpha, beta unsaturated acids, including for example, acrylic andmethacrylic acid may be added to the macromonomers, star polymers andthe polymer matrix to provide deposit resistance and in certain cases,enhanced oxygen permeability characteristics in the final copolymers.These fluoro esters include for example, perfluoroalkyl alkylmethacrylates and acrylates, telomer alcohol acrylates and methacrylatesincluding, for example, those disclosed by Cleaver in U.S. Pat. No.3,950,315, additional fluoroesters of acrylic and methacrylic acidincluding, for example, 2,2,3,3,4,4,4-heptafluorobutyl acrylate,2,2,3,4,4,4-hexafluorobutylmethacrylate as well as numerous additionalfluoro esters.

The mixture of monomers, in addition to at least one hydrophilicmonomer, may also comprise at least one crosslinking monomer.Crosslinking monomers are generally used in the star polymers of thepresent invention and are optionally used in the macromonomers, graftcopolymers and mixture of monomers of the present invention. In themixture of monomers, crosslinking monomers are generally used especiallywhen the amount of water content exceeds about 40% by weight of thefinal hydrated composition. In the case of mid to high water contentsoft contact lens copolymers, crosslinking monomers are used in varyingamounts and generally in amounts less than about 5.0% by weight,preferably about 0.05% to about 1.5% by weight and most preferably about0.2% to about 0.5% by weight of the final copolymer.

Exemplary crosslinking monomers have at least two polymerizable alpha,beta unsaturated acid esters or amides, and include, for example,ethylene dimethyacrylate, 1,3-butylene dimethacrylate,tetraethyleneglycol dimethacrylate (TEGMA), triethylene glycoldimethacrylate, trimethylolpropane trimethacrylate (TMPTMA), ethyleneglycol dimethacrylate (EGMA), 1,6-hexylene dimethacrylate, 1,4-butylenedimethacrylate, ethylene diacrylate 1,3-butylene diacrylate,tetraethyleneglycol diacrylate, triethylene glycol diacrylate,trimethylolpropane triacrylate, 1,6-hexylene diacrylate and 1,4-butylenediacrylate. Preferred crosslinking monomers for use in soft contactlenses include TEGMA, EGMA and TMPTMA, and mixtures of thesecrosslinking monomers, among others.

In general, the amount of crosslinking agent included in the starpolymers according to the present invention ranges from about 0.5% toabout 15.0%, preferably about 1% to about 3% by weight, depending uponthe size of the core that is desired. Crosslinking monomer may also beincluded in macromonomers and graft copolymers of the present inventionas well, but the inclusion of such monomers is less preferred.

The compositions according to the present invention preferably includesufficient quantities of a hydrophilic monomer to provide a finalhydrated composition comprising at least about 10% by weight water. Itis noted that in certain cases when the hydrophilic block of thepreformed copolymer contributes substantially to water content, theamount of hydrophilic monomer in the mixture of monomers may be zero.The hydrophilic monomer is generally included in the mixture of monomersto provide the contact lens with an ability to evenly disperse water onthe surface of the contact lens. Exemplary hydrophilic monomers for usein the present invention include acrylic acid, methacrylic acid,itaconic acid, fumaric acid, maleic acid, crotonic acid,N-vinylpyrrolidone, N-vinylpyridine, N-vinylcaprolactam,morpholine-containing wetting monomers, hydroxyalkylacrylates andmethacrylates including hydroxyethyl methacrylate, hydroxyethylacrylate,hydroxy-polyethoxyethylmethacrylate, polyethyleneoxide(meth)acrylate,among others, acrylamide, methacrylamide, N-isobutoxymethylacrylamide,N-isobutoxyacrylamide, N-methylolacrylamide, N-methylolmethacrylamide,glycidyl acrylate and methacrylate, dimethylaminoethylmethacrylate(DMAEMA), diethylaminoethylmethacrylate (DEAEMA), glycerol methacrylateand acrylate, among others. Many of these hydrophilic monomers also finduse for incorporation into the preformed silicone-containing copolymersaccording to the present invention. Preferred hydrophilic monomers foruse in the mixture of monomers (and, ultimately the matrix) ofcompositions of the present invention include methacrylic acid, glycerolmethacrylate, polyethyleneoxydimethacrylate, hydroxyethyl methacrylateand N-vinylpyrrolidone.

Acrylic-type hydrophilic monomers are generally included in themacromonomers, graft copolymers and star polymers of the presentinvention. Of course, one of ordinary skill in the polymer art will beable to chose the type and amount of hydrophilic monomer for use in thepreformed acrylic copolymers of the present invention. In the case ofsoft contact lens copolymers, the total amount of hydrophilic monomerincluded in the final composition which includes the polymer matrix andpreformed copolymer preferably ranges from about 20% to about 90%, mostpreferably about 60% to about 85% by weight of the final composition.

Preferred hydrophilic monomers for use in the mixture of monomers ofsoft contact lenses include hydroxyethyl methacrylate (HEMA),methacrylic acid and N-vinyl pyrrolidone (VP), and mixtures thereof withHEMA, a mixture of HEMA and methacrylic acid (the amount of methacrylicacid generally ranging from about 1% to about 8% by weight of the finalcomposition), VP and optionally methylmethacrylate (MMA) or methacrylicacid (MAA or MAC) or a mixture of VP and HEMA preferred. Particularlypreferred is a mixture of HEMA and methacrylic acid. The type and amountof hydrophilic monomer chosen will be determined by the amount and typeof silicone acrylate included in the macromonomers, stars, polymermatrix and ultimately, the final composition desired.

Many of the same acrylic-type monomers included within the mixture ofmonomers of the present invention may also be included in themacromonomers, graft copolymers or star polymers of the presentinvention. Other useful ingredients and techniques for synthesizingmacromonomers, graft copolymers and star polymers will be found in U.S.Pat. No. 4,417,034 to Webster, which is incorporated by referenceherein. Of particular note in synthesizing macromonomers, graftcopolymers and star polymers is the use of certain monomers describedhereinabove whose function it is to improve wetting or depositresistance. Preferred wetting ting monomers for this purpose include,for example, methacrylic acid, acrylic acid, dimethylaminoethylmethacrylate, diethylaminoethyl methacrylate, hydroxyethyl methacrylateand glyceryl methacrylate.

In the preparation of the macromonomer, graft and acrylic star blockcopolymers of the present invention, use may be made of the "grouptransfer" polymerization process of the general type described in partby W. B. Farnham and D. Y. Sogah, U.S. Pat. No. 4,414,372 and by O. W.Webster, U.S. Pat. No. 4,417,034 and in continuation-in-part U.S. Pat.No. 4,508,880, Webster, granted Apr. 2, 1985, and U.S. Pat. No.4,524,196 Farnham and Sogah, granted Jun. 18, 1985, all of which patentsare incorporated by reference herein.

Initiators that are useful in the polymerization of the macromonomer andstar polymers of the present invention include, among others,1-(2-trimethylsiloxy)ethoxy-1-trimethylsiloxy-2-methylpropene,methoxy-2-methyl-1-propenyl)oxy]trimethylsilane;(trimethylsilyl)isobutyronitrile; ethyl 2-(trimethylsilyl)acetate;methyl2-methyl-2-(tributylstannyl)propanoate;[(2-methyl-1-cyclohexenyl)oxy]tributylstannane; trimethylsilyl nitrile;methyl 2-methyl-2-(trimethylgermanyl)propanoate;[(4,5-dihydro-2-furanyl)oxy]trimethylsilane;[(2-methyl-1-propenylidene)bis(oxy)]bis[trimethylsilane];[(2-methyl-1-[2-(methoxymethoxy)ethoxyl]-1-propenyl)oxy]trimethylsilane;methyl [(2-methyl-1-(trimethylxilyloxy)-1-propenyl)oxy]acetate;[(1-(methoxymethoxy)-2 -methyl-1-propenyl)oxy]trimethylsilane;[(2-ethyl-1-propoxy-1-butenyl)oxy]-ethyldimethylsilane; ethyl2-(trimethylstannyl)propanoate;[(2-methyl-1-butenylidene)bis(oxy)]bis[trimethylsilane];2-(trimethylsilyl)propanenitrile; ethyl(trimethylgermanyl)acetate;[(1-((1- dec-2-enyl)oxy)-2-methyl-1-propenyl)oxy]-trimethylsilane;phenyl 2- methyl-2-(tributylstannyl)propanoate; methyl2-(triethylsilyl)acetate;[(2-methyl-1-cyclohexeneyl)oxy[tributylstannane;[(1-methoxy-2-methyl-1-propenyl)oxy]phenyldimethylsilane.

Macromonomers are linear homopolymers, block polymers, or randomcopolymers that preferably have at least one polymerizable group at oneend of the polymer chain. The polymerizable group may be a double bondfrom a methacryloxy, an acryloxy, a styrenic, an alpha methyl styrenic,an allylic, a vinylic, or other olefinic groups. Acrylic macromonomerspreferably can be prepared by the Group Transfer Polymerization processusing functional initiators and a capping process to protect thefunctional group during polymerization, by anionic polymerizationfollowed by a capping process (as described by Milkovich and Chiang,U.S. Pat. No. 3,786,116), by free radical polymerization usingfunctional chain transfer agents followed by a capping process (asdescribed by Gillman and Senogles Polymer Lett., 5, 477 (1967)), or byfree radical polymerization using special cobalt catalysts (as describedby Rizzardo, et. al., J. Macromol. Sci.-Chem., A23 (7), 839-852 (1986)).Group Transfer polymerization is the preferred method for making thesemacromonomers.

The macromonomer(s) for use in the contact lens aspect of the presentinvention preferably range in molecular weight from about 1,000 to about20,000. The more preferred range is from about 5,000 to about 15,000.The molecular weight of the macromonomers may be determined usingstandard analytical techniques, including gel permeation chromatography,light scattering, and osmometry.

Exemplary macromonomer copolymers for use in the present inventioninclude but are not limited to the following [The values given representthe weight percent of each monomer in the polymer. A double slashindicates a separation between blocks, and a single slash indicates arandom copolymer or random composition in a specific block];

    __________________________________________________________________________    Type of              Block Containing                                         Polymer                                                                              Composition   Double Bond                                                                              Molecular Weight Mn                           __________________________________________________________________________    MACRO  TRIS//TRIS/HEMA                                                                             TRIS/HEMA                                                MONOMER                                                                              75//7/18      Hydrophilic                                              MACRO  TRIS//TRIS/HEMA                                                                             TRIS/HEMA  About 14,400                                  MONOMER                                                                              33//24/42     Hydrophilic                                              MACRO  TRIS//TRIS/HEMA                                                                             TRIS/HEMA                                                MONOMER                                                                              59//11/30     Hydrophilic                                              MACRO  TRIS//TRIS/HEMA                                                                             TRIS/HEMA  About 10,000                                  MONOMER                                                                              70//12/18     Hydrophilic                                              MACRO  MAA/TRIS/HEMA//TRIS                                                                         MAA/TRIS/HEMA                                            MONOMER                                                                              2.5/14/25//58.8                                                                             Hydrophilic                                              MACRO  TRIS//HEMA/MMA                                                                              HEMA/MMA   About 10,000                                  MONOMER                                                                              60//36.5/3.5  Hydrophilic                                              __________________________________________________________________________

Such macromonomers are especially useful for forming comonomer syrupsfor bulk polymerization to form copolymers for use in oxygen-permeablecontact lenses.

In the case of soft contact lens copolymers, dramatic improvement in theoxygen permeability of these copolymers may be made by copolymerizingmacromonomers and/or star polymers with conventional monomers which formthe polymer matrix of the soft contact lens. Further enhancement of theoxygen permeability of compositions according to the present inventioncan be provided by the addition of at least about 5% by weight of thefinal composition of a silicone acrylate into the mixture of monomers.In addition, the resulting soft contact lens compositions exhibitenhanced toughness or durability relative to traditional soft contactlenses. These macromonomers and star polymers generally have a block ofa highly permeable monomer, such as a silicon acrylate (TRIS) and ablock of a hydrophilic non-silicone ester, such as HEMA or glycerylmethacrylate. The purpose of the hydrophilic block is to solubilize ordisperse the permeable block in the monomers of the polymer matrix whichalso are generally hydrophilic so that compatability occurs and a softcontact lens having favorable physical characteristics is produced.Conventional free radical initiators and crosslinking monomers are usedto provide a good balance of properties. The macromonomer may be linearor branched.

Star polymers are high molecular weight polymers that have a number oflinear, acrylic arms radiating out from a central core. The arms arelinear polymers that may be homopolymers, copolymers, or block polymers,and may have functional groups located at the end of the arms ordistributed along the chain. The cores are highly crosslinked segmentsof difunctional acrylates or copolymers of monofunctional anddifunctional acrylates. The manner in which star polymers of the presentinvention are prepared include the "arm-first", "core-first", and"arm-core-arm" methods, as described in Spinelli U.S. Pat. No. 4,810,756which is incorporated herein by reference.

The molecular weight of the arms of the star polymers may range fromabout 1,000 to about 20,000. The prefered range is from about 5,000 to14,000. The number of arms per star is dependent on the composition andprocess used to make the star. The number of arms that are present canbe determined by dividing the molecular weight of the entire star by themolecular weight of the arms. The number of arms generally range fromabout 5 to about 5,000. The preferred range is about 10 to about 200.The molecular weight of both the arms and the star can be determined byusing standard analytical techniques, such as gel permeationchromatography, light scattering, and osmometry. Factors affecting thenumber and length of arms in star polymers of the present invention arethe same as those described in U.S. Pat. No. 4,810,756. A preferrednumber average molecular weight of star polymers according to thepresent invention is about 50,000 to about 500,000.

Useful star polymers for use in the soft contact lens aspect of thepresent invention include but are not limited to the following [a singleslash indicates a random copolymer or random composition in a specificblock];

    __________________________________________________________________________    Type of                Block Containing                                                                       Molecular Weight                              Polymer                                                                            Composition       Double Bond                                                                            of Arm Mn                                     __________________________________________________________________________    STAR TRIS//HEMA/TRIS//EGDM                                                                           HEMA/TRIS                                                                              about 11,000                                       71//20/9          Hydrophilic                                            STAR TRIS//HEMA/TRIS//EGDM                                                                           HEMA/TRIS                                                                              about 11,000                                       64//20/16         Hydrophilic                                            STAR TRIS/HEMA//TRIS//Z6030/MMA                                                                      TRIS/HEMA                                                                              about 15,000                                       15/19.5//61.5//2/2                                                                              Hydrophilic                                            STAR TRIS//HEMA/TRIS   HEMA/TRIS                                                                              about 16,600                                       75//18/17         Hydrophilic                                            STAR TRIS//HEMA        HEMA     about 19,900                                       83//17            Hydrophilic                                            STAR HEMA//TRIS        HEMA     about 19,900                                       17.4//82.6        Hydrophilic                                            STAR HEMA//TRIS//Z6030/MMA                                                                           HEMA     about 31,800                                       35.5/55.6//7.1//1.8                                                                             Hydrophilic                                            __________________________________________________________________________

In the case of graft copolymers, these may be synthesized in severalways, using Group Transfer Polymerization (GTP) or free radicalpolymerization as described hereinabove. Graft copolymers may besynthesized in parts through GTP and through free radicalpolymerization, totally through GTP or totally through free radicalpolymerization. Thus, in the graft copolymers according to the presentinvention, numerous monomers may be incorporated, including, forexample, (meth)acrylates, acrylates, acrylonitriles, styrenes andolefins, among others. Using the above methodologies, graft copolymerscan be made by synthesizing the backbone first and then forming the armsoff of the backbone; synthesizing the arms first and then tying up thearms to a synthesized backbone; or synthesizing both the backbone andthe arms and then combining the backbone and arms to form the graftcopolymer.

The macromonomers, graft copolymers and star polymers preferably containpolymerizable double bonds to facilitate polymerization with themonomers of the mixture of monomers to synthesize copolymers of thepresent invention. The polymerizable double bond that is attached to themacromonomer or to the arms of the stars may be a methacryloxy, anacryloxy, a styrenic, an alpha methyl styrenic, an allylic, a vinylic,or other olefinic groups. It can be attached to the macromonomer, graftcopolymer or star polymer by reacting a functional group on the polymerwith compounds that can attach a polymerizable double bond to thepolymer. Such compounds include, for example, any molecule that has asecond functional group that can react with the first functional groupin addition to a polymerizable double bond. It is preferred that thepolymerizable double bond should be selected to promote solubility ofthe pre-formed acrylic polymer in the polymer matrix. One of ordinaryskill in the art will recognize that the chemistry of the polymerizabledouble bond may be varied to promote the solubility characteristics ofthe pre-formed copolymer.

Examples of functional groups that can be present on the macromonomer orstar polymer include hydroxy, carboxylic acid, epoxy, and aziridine. Thefunctional group may be present as such or may be present in blockedform which requires the removal of the blocking group before attachmentof the polymerizable double bond. The functional group may be attachedto the polymer through either a functional initiator or a functionalterminal monomer. Examples of the second functional group that can bereacted with the first functional group include epoxy, hydroxy, acid,aziridine, isocyanate, acid chloride, anhydride, and ester, amongothers.

Blocked hydroxyl initiators which can be used in the macromonomers andstar polymers of the present invention include1-(2-trimethylsiloxyethoxy)-1-trimethylsiloxy-2-methyl propene and1-[2-(methoxymethoxy)ethoxyl]-I-trimethylsiloxy-2-methylpropene. Blockedhydroxyl monomers which can be used include 2-(trimethylsiloxy)ethylmethacrylate, 2-(trimethylsiloxy)propyl methacrylate, and3,3-dimethoxypropyl acrylate. Blocked hydroxyl monomers which can beused include 2-(trimethylsiloxy)ethyl methacrylate,2-(trimethylsiloxy)propyl methacrylate and 3,3-dimethoxypropyl acrylate.When the polymerization is completed, the blocking group is removed togive a hydroxy functional polymer. Examples of hydroxy functionalmonomers include: 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,hydroxypropyl acrylate, and hydroxypropyl methacrylate.

Upon deblocking, the hydroxy group is then reacted with compounds thatcan attach a polymerizable double bond to the polymer. Examples of theseinclude: 2-isocyanatoethyl methacrylate, methacryloyl chloride, acryloylchloride, alpha-Methylstyrene isocyanate, acrylic acid, methacrylicacid, anhydrides of acrlic and methacrylic acid, maleic anhydride, andesters of acrylic and methacrylic acids in transesterifcation reactions.

Blocked acid initiators which can be used include1,1-bis(trimethylsiloxy)-2-methyl propene and1,1-bis(trimethylsiloxy)propene. Blocked acid monomers which can be usedinclude trimethylsiloxy methacrylate and 1-butoxyethyl methacrylate.When the polymerization is completed, the blocking group is removed togive an acid functional polymer. Acid monomers which can be used includeacrylic acid, itaconic acid, and methacrylic acid.

The acid group is then reacted with compounds that contain apolymerizable double bond and can be attached to the polymer. Examplesof these include: glycidyl acrylate and methacrylate, aziridinylacrylate and methacrylate, and hydroxy esters of acrylic and methacrylicacid.

The preformed silicone-containing acrylic copolymers, i.e.,macromonomers, graft copolymers and star polymers of the presentinvention which includes soft contact lens copolymers generally compriseabout 10.0% to about 95% by weight of the copolymer of the presentinvention, preferably about 15% to about 60% by weight of said material,and most preferably about 20% to about 50% by weight of said polymer.

Soft contact lenses made from the contact lens compositions according tothe present invention exhibit surprisingly high oxygen permeability andenhanced durability or toughness in comparison to conventional softcontact lenses while maintaining many of the favorable physicalcharacteristics of soft contact lenses including drapeability andcomfort. In addition, because the soft contact lenses according to thepresent invention in many cases exhibit greater structural integrityowing to the incorporation of macromonomers and/or star polymers, opticsof these lenses are improved relative to conventional contact lenses. Inaddition, because of the increased durability of soft contact lenspolymers of the present invention, the lenses may be made very thin, inmany cases, having a center thickness no greater than about 0.05 mm.Thus, in certain embodiments of the present invention contact lenseshaving oxygen transmissibilities (Dk/L) of greater than about ##STR9##and higher are possible.

In the method of making copolymers according to the present invention, anovel feature of the present invention relates to the bulkcopolymerization of preformed acrylic copolymer in combination with themixture of monomers which comprise the matrix. In this method of thepresent invention, the individual monomers and the preformed acryliccopolymer are mixed together to produce a liquid mixture, which issubsequently placed in a polymerization tube or a mold and thenpolymerized. The copolymer thus produced may be extruded, pressed ormolded into rods, sheets or other convenient shapes which may bemachined to the desired shape using conventional equipment andprocedures for producing contact lenses readily known to those of skillin the art. Polymerization is produced by a thermal process, by use ofultraviolet light or gamma radiation or by a combination of thesemethods. In certain cases in which the amount of preformed acryliccopolymer is very high, i.e. above about 85% by weight of thecomposition and approaching 100% by weight of the copolymer, it may benecessary to first dissolve the macromonomer and/or star polymer in anappropriate organic solvent, for example, a chlorinated hydrocarbon suchas methylene chloride, before polymerization. Where such a high weightpercentage of macromonomer, graft copolymer and/or star polymer is usedthe mixture of monomers will generally include high weight percentagesof wetting monomer. In general, the mixture of monomers that generallyform the matrix of the final composition dissolve the macromonomer,graft copolymer and star polymer to produce a viscous solution which maythen be polymerized. There is generally no need to add an organicsolvent to the mixture except where the amount of macromonomer or starpolymer is included at such a high weight percentage that the amount ofmonomer is insufficient to dissolve the macromonomer, graft copolymer orstar polymer. Alternatively, it may be possible to utilize extrusionprocesses readily available in the art to provide acceptable mixturesfor polymerization and contact lens copolymer formation.

To synthesize the compositions according to the present invention, theindividual monomers are first mixed together to produce a solution ofmonomer. Thereafter, the selected macromonomer, graft copolymer or starpolymer is then mixed with the solution of monomer and is then agitatedwith a mechanical stirrer or on an industrial tumbler (U.S. StonewareCorp. Mahwah, N.J. U.S.A.) for a few hours to about 5 days, usually forabout 3 to 5 days at low speed, e.g., about 20 rpm to about 320 rpm,preferably about 30 to 40 rpm, until the mixture is a viscoussolution/dispersion. This process of adding the macromonomer or starpolymer after the monomers are in solution reduces the difficulty ofmixing solutions/dispersions with these preformed polymers. In otherinstances, it may be found advantageous to first mix the preformedcopolyemrs with only part of the mixture of monomers before addingadditional monomer(s) to finalize the mixture. Thereafter, the mixtureis poured into button molds, tubes, or in a cast base curve radius typemold. The mixture is polymerized in the presence of at least one freeradical initiator which comprises about 0.05% to about 4.0%, preferablyno more than about 3.0% by weight of the mixture. Because of the commonoccurrence of at least two phases in the prepolymerized mixture, it hasbeen found advantageous in certain instances to include effectiveamounts of at least one hydrophobic initiator and at least onehydrophilic initiator to effectuate polymerization so that theinitiators will selectively partition into the hydrophobic andhydrophilic phases, respectively. This may result in a more completepolymerization. In certain cases polymerization may be effectuated bythe use of gamma radiation.

Polymerization initiators for use in the present invention are thosewhich are commonly used in polymerizing ethylenically unsaturatedcompounds. Representative free radical polymerization initiators includeperoxide containing compounds including acetyl peroxide, benzoylperoxide, lauroyl peroxide, decanoyl peroxide, caprylyl peroxide,tertiary-butyl peroxypivalate, diisopropyl peroxycarbonate,tertiary-butyl peroctoate and alpha, alpha'-azobisisobutyronitrile,among others . Preferred initiators for use in the present inventioninclude 2,2'-Azobis[2,4-dimethylvaleronitrile] (Vazo 52™),2-Hydroxy-2-methyl-1-phenyl-propan-2-one (Darocur 1173™),4-(2-Hydroxyethoxy)Phenyl (2-Hydroxy-2-Phenyl-(2-Hydroxy-2-Propyl)Ketone(Darocur 2959™), Irgacure 500™ (a mixture of1-hydroxycyclohexylphenylketone and benzophenone),2-Benzyl-2-(Dimethylamino)-1-[4-(4-Morpholinyl)Phenyl]-1-butanone(Irgacure 369™), 1-Hydroxycyclohexyl phenyl ketone (Irgacure 184™),2-Methyl-1-(4-(Methylthio)Phenyl) -2-(4-Morpholinyl)-1-Propanone(Irgacure 907™), Alpha, Alpha-dimethoxy-Alpha-Phenylacetophenone(Irgacure 651™), 2-Hydroxy-2-Methyl-1-Phenyl-1-Propanone andDiphenyl(2,4,6-Trimethylbenzoyl)phosphine oxide (in a 1:1 weight ratio,Darocur 4265™) and benzoinmethylether (BME). A preferred heat initiatorcombination is Vazo 52™ and t-butyl peroctoate (most preferably, inabout equal weight ratios). A preferred UV initiator combination isDarocur 1173™ and Irgacure 651™.

Conventional polymerization techniques may be used to produce thecopolymers of the present invention. Two methods of polymerization arepreferred. The first method utilizes heat; the second utilizesultraviolet light or ultraviolet light and heat. Most preferably,polymerization by ultraviolet light (either low or high intensity) isutilized.

In the case of heat polymerization of soft contact lenses, the solutionscontaining monomer mixture and preformed silicone-containing acryliccopolymer may be placed in a polymerization tube, capped and heated in awater bath or oven at a temperature ranging from about 40° C. to about90° C. for a number of hours (generally ranging from about 5 hours toabout 24 hours or more, or in a step-wise progression from 35° C. to55°-75° C. to 100°-110° C., 12-24 hours at each temperature). Thereafterthe tubes are cooled to room temperature and the rods are punched out,ground down and cut into buttons. These buttons are then lathed andpolished into contact lenses using standard procedures and then hydratedto produce soft contact lenses according to the present invention. Otherheat procedures may also be used. Heat polymerization may also be usedto produce finished contact lenses via cast-molding.

In the case of ultraviolet polymerization, ultraviolet light (low orhigh intensity at varying wavelengths depending upon the initiator used)is generally applied to the solution containing the preformedsilicone-containing acrylic copolymer in combination with the mixture ofmonomers. Irradiation is generally applied for a period ranging fromabout 10 minutes to about 120 minutes or longer. Thereafter, the buttonsare removed from the molds and then lathed, polished and hydrated bymeans readily available in the art. Alternatively and preferably,finished contact lenses are made by ultraviolet polymerization (high orlow intensity) in soft contact lens molds (base curve and/or powercurve) via cast-molding in standard plastics such as polypropylene,polystyrene, nylon, polyacrylonitrile, polycarbonate and the like for aperiod of about 10-30 minutes. Other methods well within the routineer'sskill in the art are applicable as well.

One of ordinary skill in the art will recognize that the disclosedprocedures for polymerizing contact lenses according to the presentinvention are merely exemplary and in no way should be construed tolimit the present invention in any way.

The copolymers and contact lenses of the present invention exhibitenhanced characteristics of at least one of the characteristics ofoxygen permeability, machining and durability. In the case of softcontact lenses, it is quite surprising that contact lenses could be madehaving high oxygen permeability and a toughness which would enable thecontact lens to be made with a center thickness of about 0.05 mm. In theexamples that follow, contact lenses of the present invention werecompared with lenses synthesized by a conventional random polymerizationprocess and evidenced substantially superior characteristics.

Contact lenses prepared from the copolymers according to the presentinvention generally have a refractive index ranging from about 1.35 toabout 1.50, preferably about 1.40. Contact lenses of the presentinvention preferably exhibit a Dk in excess of about 40. Dk's in excessof 45-60 are particularly preferred so that oxygen transmissibilities(Dk/L) in excess of ##STR10## are realized.

After preparation of the copolymers as described hereinabove, they arefabricated into hydrated soft contact lenses and the resultant lensesare then fitted to the eye of a patient suffering from visual deficiencyin accordance with known prior art techniques for fabricating or fittingcontact lenses.

The following examples are provided to illustrate the present inventionand should not be construed to limit the scope of the present inventionin any way.

EXAMPLES COMPARISON I

This describes the preparation of conventional soft contact lenses madeby a random copolymerization of monomers.

Formulation

The following materials were mixed together:

Hydroxyethyl methacrylate (HEMA), methacrylic acid (MAC), ethyleneglycol dimethacryalte (EGMA) and either 0.2% or 0.5% Daracure 1173™. Thesolution was poured into button molds, soft contact lens molds, orpolyethylene film molds (to make films of various thickness) andpolymerized.

Methods of Polymerization

Method 1: UV polymerization (Low Intensity). The mixture was placedunder 4 20 watt metal halide UV lamps or other low intensity UV lampsand polymerized for a period of time ranging from about 15 minutes toabout 16 hours.

Method 2: UV polymerization (High Intensity). The mixture was placedunder a Dimax PC-2 400 Watt UVA, metal halide lamp, 120 VAC, 60 Hz.

Method 3: Heat Polymerization. Mixture may be heat polymerized usingstandard heat polymerization techniques and initiators (preferablyVAZO's).

Lens Manufacturing

Lenses were polymerized in soft contact lens molds (polypropylene,polystyrene, polyethylene) and edged after polymerization.

Alternatively, a lathe was used to cut lenses using standard productionprocedures.

Results

The above formulation made good traditional contact lenses, having watercontents ranging from about 35% to about 75% and True Dk's ranging fromabout 8 to about 45. In the case of the present invention, lensmaterials having water contents ranging from about 15% to above 80% byweight and with Dk's up to about 150 have been made.

Oxygen Permeability

Oxygen permeabilities are determined using standard techniques forhydrated soft contact lens materials. A preferred method for determiningoxygen permeability in the following examples is described by IrvingFatt and Jennnifer Chaston in International Contact Lens Clinic(I.C.L.C.), 9, 76 (1982) or alternatively, Fatt and Weissman, Optom. &Vis. Sci., 66, (4) 235-238 (1989). The contact lens materials testedranged in thickness from about 0.07 to about 0.45 (preferably about 0.1to about 0.3). The values given are the diffusion constants: ##STR11##

Transmissibility numbers are provided as Dk/L ##STR12##

Measured Dk's are determined on a O₂ Permeometer™ Model 201T byCreatech, Albany, Calif.

True Dk's are determined using three thickness and determining the slopeof a graph of (L vs. L/Dk) using linear regression. One point calculatedDk's are determined using the following formula: ##EQU1##

Water Content Measurements

Water content is determined one of two ways. In the first method, afreshly polymerized lens is weighed and then hydrated. The water contentis determined by simply subtracting the dry weight from the hydratedweight and then dividing by the hydrated weight.

Alternatively, and preferably, water content is determined by firstextracting any unreacted monomer for 18 hours in boiling 0.1M aqueousphosphate or bicarbonate buffer (pH 7.5-8), drying the lens andsubsequently hydrating the lens. Lenses are hydrated in distilled waterfor a period of at least about 1 hour or until equilibrium is reached(which may vary depending upon the chemical composition of the contactlens). Water content is determined by subtracting the dry weight fromthe hydrated weight and then dividing by the hydrated weight.

COMPARISONS

The following presents a series of soft contact lenses which is made bycopolymerization of hydroxyethylmethacrylate (HEMA), methacrylic acid(MAC) and ethylene glycol dimethacrylate (EGMA). The EGMA is added tothe monomer mixture to crosslink the lens material and provide greaterstructural integrity to the softlens material.

    ______________________________________                                        Formulation                                                                   Com-                            Initiator                                                                            Properties                             parison                         Daracure    True                              Runs    HEMA     MAC     EGMA   1173   H.sub.2 O                                                                          DK                                ______________________________________                                        1       99.5     0       0.5    0.2    35.8 8.5                               2       98.5     1       0.5    0.2    42.5 11                                3       97.5     2       0.5    0.5    49.3 15                                4       96.5     3       0.5    0.2    54.3 19                                5       95.5     4       0.5    0.2    61.4 24                                6       93.5     6       0.5    0.2    69.5 35                                7       91.5     8       0.5    0.2    76.2 45                                ______________________________________                                    

The above table shows the results that are obtained with conventionalrandom copolymerization of traditional hydrophilic monomers.

The results from Comparisons 1 to 7 are standard for lenses made from arandom copolymerization of hydrophilic monomers such as HEMA and MAC.These results indicate that as the water content of a contact lensmaterial increases, the oxygen permeability increases. At very highwater contents (>70%), the toughness and structural integrity of thelens materials decreases.

EXAMPLES 1-29

In the examples that follow, the compositions are expressed in terms ofthe weight ratios of the final compositions. The following describe thecomposition and synthesis of star polymers that have arms that arediblocks (hydrophilic and hydrophobic blocks), cores that areethyleneglycol dimethacrylate or silicone (Z6030-polysiloxane), and apolymerizable double bond attached to the hydrophilic block of the arms.The examples also describe the use of macromonomers that are generallydiblocks (hydrophilic and hydrophobic) and have polymerizable doublebonds incorporated into the hydrophilic block of the copolymers.

The following show the advantages obtained by using star andmacromonomer polymers in soft contact lens formulations.

Preparation Procedure for Lenses Made with Stars or Macromonomers I.Mixing Procedure

All liquid ingredients were weighed and mixed in screw-on-cap bottlesshaken and stirred or tumbled for a period ranging from an hour toseveral days. The star or macromonomer generally was weighed and addedto the liquid ingredients in small portions (from 10% to 50% by weight).In order to disperse the powder in the bulk of the mixture, after eachaddition the mixture was stirred using a magnetic stirrer or othermechanical stirrer, the bottle then capped and sealed properly, tumbledon a roller mill until the solution was clear and homogeneous (from onehour to several days). In certain instances, the mixture had to befiltered before use. The initiator and optionally, pigment were addedand tumbled for half an hour, then poured into molds, tubes, or spreadonto plates for forming polymeric films. In certain aspects of theinvention, the prepolymerized mixtures, because of their reducedviscosity, are polymerized in molds using a spin-casting process whichis readily known in the art.

II. Polymerization Procedure Thermal Polymerization:

In general, solutions were poured into molds and put in a water bath oran oven for about one hour to 18 hours or more at varying temperatures(generally about 40° C. to about 75° C. or higher). The molds or tubesin certain cases were then further heated at a slightly highertemperature and finally the temperature was raised to 110° C. for anumber of hours (usually for at least a few hours up to about 6-8hours). Sometimes an extra 24 hours at 130° C. was used. The tubes ormolds were cooled to room temperature and the rods, molded buttons,films or final lenses were punched out or otherwise removed. The rodswere ground to approximately one half inch diameter and cut to buttons.The buttons from rods or molds were cut and lathed into lenses. Thefinished lenses were simply removed from the molds and edged, whereneeded. The lenses or films were thereafter hydrated, generally in 0.1Mphosphate buffer, pH about 7.5 to 8-9. Dk was determined on lenses orfilms of varying thicknesses using standard procedures well known in theart.

The Ultraviolet Method

After the solution was prepared, it was poured in button molds andplaced in a UV box. Nitrogen and vacuum was applied alternatively.Irradiation was applied for 10 to 45 minutes or longer under nitrogenatmosphere under low intensity UV or high intensity UV light (Dimaxunit) as previously described. The molds were then removed oralternatively, heated for one to several hours at a temperature rangingfrom about 80° C. to 110° C. for purposes of producing a post-cure.Lenses or buttons were punched out of the molds and faced or polished.

III. Lens Manufacturing

A lathe cut lenses from buttons using standard production procedures.Alternatively, and preferably, the soft contact lenses were polymerizedin a soft contact lens mold (polypropylene) using Darocure 1173™ or acombination of Darocur 1173™ and Irgacure 651™ (approximately 1:1 weightratio) under low or high intensity UV light for a period ranging fromabout ten minutes to an hour or more, removed and hydrated.

Soft Contact Lenses

A number of macromonomers and star polymers were synthesized andincorporated into soft contact lens polymer matrices. The resultingcopolymers were then tested for oxygen permeability as a function ofwater content. The following are examples of the synthesis ofmacromonomers and star polymers for use in the soft contact lens aspectof the present invention. For purposes of this discussion, the followinglegend is applicable:

// indicates a block copolymer of the components separated by thatsymbol;

/ indicates a random copolymer of the components separated by thatsymbol.

HEMA=2-hydroxyethylmethacryalte, incorporated into the preformed acryliccopolymer as TMS-HEMA (2-(trimethylsiloxy)ethylmethacryate) which isthen hydrolyzed to give HEMA.

Z6030=3-(trimethyloxysilyl)propyl methacrylate.

MMA=methyl methacrylate.

EDGMA=ethylene glycol dimethacrylate.

EXAMPLE 1 TRIS//HEMA/TRIS 70//18/12 Linear Block Copolymers

This reaction sequence describes the preparation of a linear blockcopolymer that has a block of3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS) and a randomblock containing TRIS and 2-hydroxyethylmethacrylate (HEMA). The TRISblock is prepared first. The double bonds are put in by reaction ofhydroxy groups with an isocyanate. There is an average of 3.7 doublebonds in each polymer chain and are located in either/both block.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. TRIS, 163 g;THF, 52 g; bis(dimethylamino)methylsilane (BDMAMS), 2.9 g; p-xylene, 3.2g; and tetrabutylammonium m-chlorobenzoate (TBACB), 300 uL of a 1.0M THFsolution were charged to the pot. Initiator1-(2trimethylsiloxy)ethoxy-1-trimethylsiloxy-2-methylpropene, 5.6 g wasinjected. Feed I (TBACB, 400 uL and THF, 50.3 g) was started and addedover 600 min. The TRIS block was polymerized to about 85% conversionafter 175 min. At this time, Feed II(2-(trimethylsiloxy)ethylmethacrylate, 56.4 g, TBACB, 200 uL and BDMAMS,0.6 g) was started and added over 250 min. The reaction was allowed tostir overnight under nitrogen atmosphere. The next morning, the reactionwas quenched with methanol, 50.2 g, water, 55.8 g; dichloroacetic acid,375 uL and THF, 200 g. It was refluxed for 4 hours. Then 630 g ofsolvent was distilled off while 240 g of toluene was added. The contentsof the flask was distilled until the vapor temperature equaledapproximately 110° C. alpha-Methylstyrene isocyanate (TMI from AmericanCyanamid), 13.8 g and dibutyltin dilaurate, 300 uL were added andrefluxed for 4.5 hours. This put double bonds at any of thehydroxy-containing sites in the polymer chain. The average number ofdouble bonds in each polymer chain is 4. Butanol, 25 g was added andrefluxed for 3 hours. The polymer solution was then dried in a vacuumoven.

This made a linear block copolymer of TRIS/HEMA//TRIS 70//18/12 with aMn of 10,000 and Mw of 18,800.

EXAMPLE 2 TRIS//HEMA/TRIS 33//42/24 Linear Block Copolymers

This reaction sequence describes the preparation of a linear blockcopolymer that has a block of3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS) and a randomblock containing TRIS and 2-hydroxyethylmethacrylate (HEMA). The TRISblock is prepared first. The double bonds are put in by reaction ofhydroxy groups with an isocyanate. There is an average of 4.2 doublebonds in each polymer chain and are located in either/both block.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. TRIS, 73.4 g;THF, 51 g; bis(dimethylamino)methylsilane (BDMAMS), 1.1 g; p-xylene, 3.3g; and tetrabutylammonium m-chlorobenzoate (TBACB), 400 uL of a 1.0M THFsolution were charged to the pot. Initiator1-(2trimethylsiloxy)ethoxy-1-trimethylsiloxy-2-methylpropene, 5.2 g wasinjected. Feed I (TBACB, 400 uL and THF, 53.8 g) wa started and addedover 600 min. The TRIS block was polymerized to about 91 % conversion.At this time, TRIS, 41.9 g; and BDMAMS, 0.8 g; were added in one shot.Then Feed II (2-(trimethylsiloxy)ethylmethacrylate, 130.9 g, TBACB, 200uL and BDMAMS, 1.6 g) was started and added over 240 min. The reactionwas allowed to stir overnight under nitrogen atmosphere. The nextmorning, the reaction was quenched with methanol, 106.1 g, water, 119.4g; dichloroacetic acid, 800 uL and THF, 850 g. It was refluxed for 4hours. Then solvent was distilled off while toluene was added. Thecontents of the flask was distilled until the vapor temperature equaledapproximately 110° C. alpha-Methylstyrene isocyanate (TMI from AmericanCyanamid), 14.7 g and dibutyltin dilaurate, 300 uL were added andrefluxed overnight. This put double bonds at any of thehydroxy-containing sites in the polymer chain. Butanol, 2 g was addedand refluxed for 1 hour. The polymer solution was then dried in a vacuumoven.

This made a linear block copolymer of TRIS/HEMA//TRIS 33//42/24 with aMn of 14,400 and Mw of 22,000.

EXAMPLE 3

MAA/TRIS/HEMA//TRIS 2.5/14/25//58.8 Linear Block Copolymers

This reaction sequence describes the preparation of a linear polymerthat has a random block containing TRIS and 2-hydroxyethylmethacrylate(HEMA) and a block of 3-methacryloxypropyltris-(trimethylsiloxy)silane(TRIS). The HEMA/TRIS random block is prepared first. The double bondsin this polymer is put in by the reaction of acid groups with glycidylmethacrylate. There is an average of 3.5 double bonds in each polymerchain and are located only in the HEMA/TRIS block.

A 3 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. THF, 71.6 g;initiator 1,1-bis(trimethylsiloxy)2-methylpropene, 8.1 g; TBACB, 250 uLand p-xylene, 3.8 g were charged to the pot. Feed I (TBACB, 600 uL andTHF, 22 g) was started and added over 400 min. Feed IItrimethylsilylmethacrylate, 12.2 g,(2-(trimethylsiloxy)-ethylmethacrylate, 97 g, TRIS, 35.5 g, TBACB 250 uLand BDMAMS, 1.4 g) was started over 30 min. After 145 min. Feed III(TRIS, 148.1 g; BDMAMS 1.6 g and TBACB, 250 uL) was added over 10 min.After stirring overnight, THF, 200 g was added. The reaction wasquenched with methanol, 16 g; water and benzyltrimethylammoniumhydroxide, 9.0 g of a 40% solution in methanol. The reaction wasrefluxed for 60 min. Toluene, 480 g, was added. Solvents, 450 g, wasdistilled off. The reaction was cooled to about 80° C. and another 8.85g of a 40% methanol solution of benzyltrimethylammonium hydroxide wasadded. Feed IV (glycidyl methacrylate, 15.4 g) was started and addedover 3.5 hours. After completion of feed, the reaction was allowed tostir at 80° C. and the consumption of glycidyl methacrylate was followedby HPLC. When all of the glycidyl methacrylate was consumed, thereaction mixture was dried in a vacuum oven.

EXAMPLE 4 TRIS/HEMA//TRIS//Z6030/MMA 8.7/16//70//2.5/2 Star

This reaction sequence describes the preparation of a star polymer thathas arms composed of a random block of TRIS and HEMA and a block ofTRIS. The TRIS block was prepared first. The core is composed of Z6030and MMA. There is an average of 3 double bonds in each polymer chain andare located in the block containing the HEMA.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. Z6030, 10.3 g;THF, 19.0 g; MMA, 8.1 g; TRIS, 17.7 g; BDMAMS, 0.5 g; p-xylene, 3.5 g;and TBACB, 400 uL of a 1.0M THF solution were charged to the pot.Initiator 1-methoxy-1-trimethylsiloxy-2-methylpropene, 7.1 g wasinjected. Feed I (TBACB, 810 uL and THF, 40.8 g) was started and addedover 200 min. After 15 min. Feed II (TRIS, 303.9 g; and BDMAMS, 13.11 g)was added all at once. The TRIS block was polymerized to about 89% after125 min. and Feed III (THF, 48.3 g;2-(trimethylsiloxy)ethylmethacrylate, 100.5 g; TBACB, 400 uL and BDMAMS,2.99 g) was started and added over 280 min. The reaction was allowed tostir overnight under nitrogen atomosphere. The next morning, thereaction was quenched with methanol, 80.4 g; water 90.4 g;dichloroacetic acid, 605 uL and THF, 763 g. It was refluxed for 4 hours.Then 1302 g of solvent was distilled off while 486 g of toluene wasadded. The contents of the flask was distilled until the vaportemperature equaled approximately 110° C. alpha-Methylstyrene isocyanate(TMI from American Cyanamid), 22.9 g and dibutyltin dilaurate, 440 uLwere added and refluxed for 4 hours. This put double bonds at any of thehydroxy-containing sites in the polymer chain. The average number ofdouble bonds in each polymer chain is 2. The polymer solution was thendried in a vacuum oven.

This made a star polymer of TRIS/HEMA//TRIS//Z6030/MMA 8.7/16//70//2.5/2stars with a Mn of 15,000, Mw=37,000.

EXAMPLE 5 TRIS//HEMA/TRIS 75//18/7 Star

This reaction sequence describes the preparation of a star polymer thathas arms composed of a random block of TRIS and HEMA and a block ofTRIS. The TRIS block is prepared first. There is an average of 2.9double bonds in each polymer chain and are all located in the blockcontaining the HEMA. The core of the star is formed by the condensationof the initiator groups.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. TRIS, 150.1 g;THF, 5.9 g; BDMAMS, 2.2 g; p-xylene, 3.5 g; and TBACB, 200 uL of a 1.0MTHF solution were charged to the pot. Initiator1-(3-trimethoxylsilyl)propyloxy-1-trimethylsiloxy-2-methylpropene, 6.13g was injected. Feed I (TBACB, 400 uL and THF, 43.5 g) was started andadded over 600 min. The TRIS block was polymerized to about 88%conversion after 300 min. At this time, Feed II (THF, 66.8 g;2-(trimethylsiloxy)ethylmethacrylate, 49.1 g and BDMAMS, 1.3 g) wasstarted and added over 15 min. The reaction was allowed to stirovernight under nitrogen atomosphere. The next morning, the reaction wasquenched with methanol, 40.7 g; water 22.3 g; dichloroacetic acid, 220uL and THF, 950 g. It was refluxed for 4 hours. Then 1100 g of solventwas distilled of while 260 g of toluene was added. The contents of theflask was distilled until the vapor temperature equaled approximately110° C. alpha-Methylstyrene isocyanate (TMI from American Cyanamid),10.2 g and dibutyltin dilaurate, 200 uL were added and refluxed for 4hours. This put double bonds at any of the hydroxy-containing sites inthe polymer chain. The average number of double bonds in each polymerchain is 2. Butanol, 15 g was added and refluxed for 0.5 hour. Thepolymer solution was then dried in a vacuum oven.

This made a star polymer of TRIS//HEMA/TRIS 75//18/7 with a Mn of16,600, Mw of 33,800.

EXAMPLE 6 TRIS//HEMA 75//25 Star

This reaction sequence describes the preparation of a star polymer thathas arms composed of a block of TRIS and a block of HEMA. The TRIS blockis prepared first. There is an average of 2 double bonds in each polymerchain and are all located in the block containing the HEMA. The core ofthe star is formed by the condensation of the initiator groups.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. TRIS, 454.3 g;THF, 152.7 g; BDMAMS, 6.3 g; p-xylene, 4.5 g; and TBACB, 900 uL of a1.0M THF solution were charged to the pot. Initiator1-(3-trimethoxylsilyl)propyloxy-1-trimethylsiloxy-2-methylpropene, 20.28g was injected. Feed I (TBACB, 600 uL and THF, 10.2 g) was started andadded over 330 min. The TRIS block was polymerized to about greater than98% conversion. At this time, Feed II (THF, 306.0 g;2-(trimethylsiloxy)ethylmethacrylate, 226.3 g;) was started and addedover 30 min. The reaction was allowed to stir overnight under nitrogenatomosphere. The next morning, the reaction was quenched with methanol,101.7 g; water 60.0 g; dichloroacetic acid, 1000 uL and THF, 453 g. Itwas refluxed for 4 hours. Then 340 g of solvent was distilled off while658 g of toluene was added. The contents of the flask was distilleduntil the vapor temperature equaled approximately 110° C.alpha-Methylstyrene isocyanate (TMI from American Cyanamid), 18 g anddibutyltin dilaurate, 240 uL were added and refluxed for 4 hours. Thisput double bonds at any of the hydroxy-containing sites in the polymerchain. Butanol, 23 g was added and refluxed for 1 hour. The polymersolution was then dried in a vacuum oven.

This made a star polymer of TRIS//HEMA 75//25 with a Mn of 19,900, Mw of128,900.

EXAMPLE 7 HEMA//TRIS 17.4//82.6 Star

This reaction sequence describes the preparation of a star polymer thathas arms composed of a block of HEMA and a block of TRIS. The TRIS blockis prepared first. The core is composed of a polysiloxane material.There is an average of 1.5 double bonds in each polymer chain and arelocated in the block containing the HEMA.

A 1 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. TRIS, 75.0 g;THF, 25.1 g; p-xylene, 2.0 g; BDMAMS, 1.0 gm; and TBACB, 150 uL of a1.0M THF solution were charged to the pot. Initiator1-[3-(trimethoxysilyl)propoxyl]-1-trimethylsiloxy-2-methylpropene, 3.34g was injected. Feed I (TBACB, 100 uL and THF, 4.0 g) was started andadded over 200 min. After 180 min., the TRIS block was polymerized. FeedII (THF, 50.0 g; 2-(trimethylsiloxy)ethylmethacrylate, 24. g;) wasstarted and added over 10 min. The reaction was allowed to stirover-night under nitrogen atomosphere. The next morning, the reactionwas quenched with methanol, 20.0 g; water 11.0 g; dichloroacetic acid,100 uL and THF, 75 g. It was refluxed for 4 hours. Then 280 g of solventwas distilled of while 200 g of toluene was added. The contents of theflask was distilled until the vapor temperature equaled approximately110° C. alpha-Methylstyrene isocyanate (TMI from American Cyanamid), 3.0g and dibutyltin dilaurate, 40 uL were added and refluxed for 4 hours.This put double bonds at any of the hydroxy-containing sites in thepolymer chain. The average number of double bonds in each polymer chainis 1.5. The polymer solution was then dried in a vacuum oven.

This made a star polymer of HEMA//TRIS 17.4//82.6 with a Mn of 19,900,Mw=34,400.

EXAMPLE 8 HEMA//TRIS//Z6030/MMA 35.5//55.6//7.1/1.8 Star

This reaction sequence describes the preparation of a star polymer thathas arms composed of a block of HEMA and a block of TRIS. The TRIS blockis prepared first. The core is composed of Z6030 and MMA. There is anaverage of 2.0 double bonds in each polymer chain and are located in theblock containing the HEMA.

A 1 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tupe outlet and additional funnels. Z6030 15.9 g.and MMA, 4.0 gm; p-xylene, 2.0 g; and TBACB, 400 uL of a 1.0M THFsolution were charged to the pot. Initiator1-methoxy-1-trimethylsiloxy-2-methylpropene, 3.5 g was injected. Feed I(TBACB, 100 uL and THF, 4.0 g) was started and added over 200 minutes.After 20 min. Feed II (TRIS, 125.3 g; TBACB, 100 uL of a 1.0M THFsolution and BDMAMS, 2.0 g) was added over 10 minutes. The TRIS block ws polymerized. At 330 minutes into the reaction, Feed III (THF, 99.0 g;2-(trimethylsiloxy)ethylmethacrylate, 124.0 g) was started and addedover 10 min. The reaction was allowed to stir overnight under nitrogenatmosphere. The next morning, the reaction was quenched with methanol,100.0 g; water, 55.0 g; dichloroacetic acid, 400 uL and THF, 150 g. Itwas refluxed for 4 hours. Then 380 g of solvent was distilled off while580 g of toluene was added. The contents of the flask was distilleduntil the vapor temperature equaled approximately 100° C.alpha-Methylstyrene isocyanate (TMI from American Cyanamid), 8.1 g anddibutyltin dilaurate, 100 uL were added and refluxed for 4 hours. Thisput double bonds at any of the hydroxy-containing sites in the polymerchain. The average number of double bonds in each polymer chain is 2.The polymer solution was then dried in a vacuum oven.

This made a star polymer of HEMA//TRIS//Z6030/MMA 35.5//55.6//7.1/1.8with a Mn of 31,800, Mw=771,000.

EXAMPLE 9

TRIS//HEMA/TRIS 59//30/11 Linear Block Copolymers

This reaction sequence describes the preparation of a linear blockcopolymer that has a block of3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS) and a randomblock containing TRIS and 2-hydroxyethylmethacrylate (HEMA). The TRISblock is prepared first. The double bonds are put in by reaction ofhydroxy groups with an isocyanate. There is an average of 4 double bondsin each polymer chain and are located in either/both block.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. TRIS, 145.4 g;THF, 48.9 g; bis(dimethylamino)methylsilane (BDMAMS), 2.6 g; p-xylene,3. g; and tetrabutylammonium m-chlorobenzoate (TBACB), 420 uL of a 1.0MTHF solution were charged to the pot. Initiator1-(2trimethylsiloxy)ethoxy-1-trimethylsiloxy-2-methylpropene, 5.61 g wasinjected. Feed I (TBACB, 420 uL and THF, 51.5 g) was started and addedover 600 min. The TRIS block was polymerized to about 85% conversion. Atthis time, Feed II (2-(trimethylsiloxy)ethylmethacrylate, 96.2 g, TBACB,210 uL and BDMAMS, 0.98 g) was started and added over 300 min. Thereaction was allowed to stir overnight under nitrogen atmosphere. Thenext morning, the reaction was quenched with methanol, 80.0 g, water,90.0 g; dichloroacetic acid, 600 uL and THF, 540 g. It was refluxed for4 hours. Then solvent was distilled off while 200 g of toluene wasadded. The contents of the flask was distilled until the vaportemperature equaled approximately 110° C. alpha-Methylstyrene isocyanate(TMI from American Cyanamid), 14.8 g and dibutyltin dilaurate, 300 uLwere added and refluxed overnight. This put double bonds at any of thehydroxy-containing sites in the polymer chain. Butanol, 22 g was addedand refluxed for 0.5 hour. The polymer solution was then dried in avacuum oven.

This made a linear block copolymer of TRIS/HEMA//TRIS 59//30/11 with aMn of 17,500

EXAMPLE 10 TRIS/HEMA//TRIS//Z6030/MMA 14.1/18.6//63.6//2.0/1.7 Star

This reaction sequence describes the preparation of a star polymer thathas arms composed of a random block of TRIS and HEMA and a block ofTRIS. The TRIS block was prepared first. The core is composed of Z6030and MMA. There is an average of 4.6 double bonds in each polymer chainand are located in the block containing the HEMA.

A 2 liter flask is equipped with a mechanical stirrer, thermometer,nitrogen inlet, drying tube outlet and addition funnels. Z6030, 10.0 g;THF, 20.2 g; MMA, 8.2 g; TRIS, 17.1 g; BDMAMS, 0.5 g; p-xylene, 2.2 g;and TBACB, 405 uL of a 1.0M THF solution were charged to the pot.Initiator 1-methoxy-1-trimethylsiloxy-2-methylpropene, 6.88 g wasinjected. Feed I (TBACB, 810 uL and THF, 43.5 g) was started and addedover 200 min. After 10 min. Feed II (TRIS, 366.6 g; and BDMAMS, 2.91 g)was added all at once. The TRIS block was polymerized to about 81% after70 min. and Feed III (THF, 52.6 g; 2-(trimethylsiloxy)ethylmethacrylate,142.5 g; TBACB, 400 uL and BDMAMS, 3.05 g) was started and added over280 min. The reaction was allowed to stir overnight under nitrogenatomosphere. The next morning, the reaction was quenched with methanol,110.1 g; water 80.5 g; dichloroacetic acid, 860 uL and THF, 297 g. Itwas refluxed for 4 hours. Then solvent was distilled off while 332 g oftoluene was added. The contents of the flask was distilled until thevapor temperature equaled approximately 110° C. alpha-Methylstyreneisocyanate (TMI from American Cyanamid), 33.2 g and dibutyltindilaurate, 660 uL were added and refluxed for 4 hours. This put doublebonds at any of the hydroxy-containing sites in the polymer chain. Thepolymer solution was then dried in a vacuum oven.

This made a star polymer of TRIS/HEMA//TRIS//Z6030/MMA14.1/18.6//63.6//2.0/1.7 star with a Mn of 14,200, Mw=206,000.

EXAMPLE 11 TRIS//HEMA/MMA 60//36.5/3.5 Linear Block Copolymers

This reaction sequence describes the preparation of a linear copolymercomprising a block of 3-methacryloxypropyltris(trimethylsiloxy)silane(TRIS) and a block containing both methyl methacrylate (MMA) and2-hydroxyethyl methacrylate (HEMA). There is on the average 2 doublebonds per polymer chain distributed in the HEMA/MMA block.

A 5 liter flask was equipped with a mechanical stirrer, thermometer, N2inlet, drying tube outlet and addition funnels. Tetrahydrofuran, 196 g,tetrabutylammonium m-chlorobenzoate, 1.8 mL,bis(dimethylamino)methylsilane, 3.8 g, p-xylene, 9 g and TRIS, 552 g,were charged to the pot. Initiator,1-trimethylsiloxy-1-methoxy-2-methylpropene, 16.0 g was injected and theTRIS block was polymerized. Feed 1 (THF, 20 g and tetrabutylammoniumm-chlorobenzoate, 4 mL of a 1.0M solution in THF) was then started andadded over 200 min. Feed 2 (2-trimethylsiloxy)ethyl methacrylate, 529 g,MMA, 27.6 g, and bis(dimethylamino)methylsilane, 1.3 g) was started at40 min. after the addition of the initiator. Feed 2 was added over aperiod of 180 minutes. A total of 220 g of THF wa added to reduce theviscosity of the reaction mixture. One hour after the addition of Part2, the reaction was quenched with methanol, 419 g, water, 236 g,dichloroacetic acid, 0.43 ml and THF, 1168 g. The mixture was refluxedfor 4 hours. Solvent, 2200 g was distilled off while 2000 g of toluenewas added. The contents of the flask were distilled until the vaportemperature equalled approximately 107° C. Then dibutyltin dilaurate,0.51 mL, and alpha-methylstyrene isocyanate (TMI from Am. Cyanamid),34.7 g was added and refluxed for 5 hours. Dried n-butanol, 5.3 g, wasadded and refluxed for 30 min. This puts an average of about 2 doublebonds per polymer chain. Another 250 g of solvent was removed and theremaining solution dried in a vacuum oven.

This made a linear block copolymer TRIS//HEMA/MMA 60//36.5/3.5 having anMn of approximately 10,000.

EXAMPLE 12 TRIS//HEMA/MMA 68//29/3 Linear Block Copolymers

This reaction sequence describes the preparation of a linear copolymercomprising a block of3-methacryloxypropyltris(trimethylsiloxy)silane(TRIS) and a blockcontaining both methyl methacrylate (MMA) and 2-hydroxyethylmethacrylate (HEMA). There is an average of 2 double bonds per polymerchain distributed in the HEMA/MMA block.

A 12 liter flask was equipped with a mechanical stirrer, thermometer, N2inlet, drying tube outlet and additional funnels. Tetrahydrofuran, 786g, tetrabutylammonium m-chlorobenzoate, 6.4 mL, bis(dimethylamino)methylsilane, 20.6 g, p-xylene, 32 g and TRIS, 2213 g, were charged to thepot. Initiator, 1-trimethylsiloxy-1-methoxy-2-methylpropene, 57.2 g, wasinjected and the TRIS block was polymerized. Feed 1 (THF, 20 g andtetrabutylammonium m-chlorobenzoate, 13 mL of a 1.0M solution in THF)was then started and added over 200 min. Feed 2(2-trimethylsiloxy)ethylmethacrylate, 1472 g, MMA, 92 g andbis(dimethylamino)methylsilane was started at 60 min. after the additionof initiator. Feed 2 was added over a 180 min. period. A total of 3733 gof THF was added to reduce the viscosity of the reaction mixture. Onehour after the addition of Part 2, the reaction was quenched withmethanol, 769 g, water, 461 g, dichloroacetic acid, 1.0 mL. The mixturewas then refluxed for 5 hours. Solvent was distilled off while 5000 g oftoluene was added. The contents of the flask were distilled until thevapor temperature equalled approximately 107° C. Then dibutyltindilaurate, 2.4 mL, and alpha-methylstyrene isocyanate (TMI from AmericanCyanamid), 137 g was added and refluxed for 5 hours. Dried n-butanol, 15g, was added and refluxed for 15 min. This puts an average of about 2double bonds per polymer chain. The remaining solution was dried in avacuum oven.

This made a linear block copolymer TRIS/HEMA/MMA 68//29/3 having an Mnof approximately 10,000.

EXAMPLE 13 TRIS//HEMA/TRIS 63//30/7 Linear Block Copolymers

This reaction sequence describes the preparation of a linear copolymercomprising a block of3-methacryloxypropyltris(trimethylsiloxy)silane(TRIS) and a blockcontaining both methyl methacrylate (MMA) and3-methacryloxypropyltris(trimethylsiloxy)silane(TRIS). There is anaverage of 2 double bonds per polymer chain distributed in the HEMA/TRISblock.

A 5 liter flask was equipped with a mechanical stirrer, thermometer, N2inlet, drying tube outlet and additional funnels. Tetrahydrofuran, 99.4g, tetrabutylammonium m-chlorobenzoate, 0.800 mL,bis(dimethylamino)methyl silane, 3.87 g, p-xylene, 5.76 g and TRIS,279.9 g, were charged to the pot. Initiator,1-trimethylsiloxy-1-methoxy-2-methylpropene, 7.12 g, was injected andthe TRIS block was polymerized. Feed 1 (THF, 50 g and tetrabutylammoniumm-chlorobenzoate, 1.2 mL of a 1.0M solution in THF) was then started andadded over a 600 min. period. Feed 2 (2-(trimethylsiloxy)ethylmethacrylate and bis(dimethylamino)methylsilane, 1.79 g) was started at70 minutes after the addition of initiator. Feed 2 was added over 300minutes. Twelve hours after the addition of Part 2, the reaction wasquenched with methanol, 143 g, water, 56 g, dichloroacetic acid, 0.700mL and THF, 487 g. The mixture was refluxed for 4 hours. The mixture wasthen refluxed for 4 hours. Solvent was distilled off while 200 g oftoluene was added. The contents of the flask were distilled until thevapor temperature equalled approximately 107° C. Exactly one-quarter ofthe contents of the flask was subjected to the following treatment toput pendant double bonds onto the polymer. Dibutyltin dilaurate, 0.090mL, and alpha-methylstyrene isocyanate (TMI from American Cyanamid), 4.5g were added and refluxed for 5 hours. Dried n-butanol, 1 g, was addedand refluxed for 30 min. This puts an average of about 2 double bondsper polymer chain. The solution was dried in a vacuum oven.

This made a linear block copolymer TRIS//HEMA/TRIS 63//30/7 having an Mnof approximately 10,000 and Mw of about 19,100.

EXAMPLE 14 TRIS//HEMA/TRIS 63//30/7 Linear Block Copolymer

This reaction sequence describes the preparation of a linear copolymercomprising a block of3-methacryloxypropyltris(trimethylsiloxy)silane(TRIS) and a blockcontaining both methyl methacrylate (MMA) and3-methacryloxypropyltris(trimethylsiloxy)silane(TRIS). There is anaverage of 4.5 double bonds per polymer chain distributed in theHEMA/TRIS block.

A 5 liter flask was equipped with a mechanical stirrer, thermometer, N2inlet, drying tube outlet and additional funnels. Tetrahydrofuran, 99.4g, tetrabutylammonium m-chlorobenzoate, 0.800 mL,bis(dimethylamino)methyl silane, 3.87 g, p-xylene, 5.76 g and TRIS,279.9 g, were charged to the pot. Initiator,1-trimethylsiloxy-1-methoxy-2-methylpropene, 7.12 g, was injected andthe TRIS block was polymerized. Feed 1 (THF, 50 g and tetrabutylammoniumm-chlorobenzoate, 1.2 mL of a 1.0M solution in THF) was then started andadded over a 600 min. period. Feed 2 (2-(trimethylsiloxy)ethylmethacrylate and bis(dimethylamino)methylsilane, 1.79 g) was started at70 minutes after the addition of initiator. Feed 2 was added over 300minutes. Twelve hours after the addition of Part 2, the reaction wasquenched with methanol, 143 g, water, 56 g, dichloroacetic acid, 0.700mL and THF, 487 g. The mixture was refluxed for 4 hours. The mixture wasthen refluxed for 4 hours. Solvent was distilled off while 200 g oftoluene was added. The contents of the flask were distilled until thevapor temperature equalled approximately 107° C. Exactly one-quarter ofthe contents of the flask was subjected to the following treatment toput pendant double bonds onto the polymer. Dibutyltin dilaurate, 0.180mL, and alpha-methylstyrene isocyanate (TMI from American Cyanamid), 9.0g were added and refluxed for 5 hours. Dried n-butanol, 2 g, was addedand refluxed for 30 min. This puts an average of about 4.5 double bondsper polymer chain. The remaining solution was dried in a vacuum oven.

This made a linear block copolymer TRIS//HEMA/TRIS 63//30/7 having an Mnof approximately 10,000.

EXAMPLES 15-18

The macromonomer of example 1 was combined with hydrophilic monomers asexhibited in Table 2. Specifically, soft contact lenses comprising thismacromonomer ranging in weight from 21.5 to 33.5 were copolymerized withmixtures of HEMA, MAC, VP and EGDM in the indicated weight ratios. Aftermixing the macromonomer and monomers, the mixture was placed in moldsunder UV light in the absence of oxygen for approximately 1 hour. Afterremoving the buttons from the molds, the copolymers were then machinedinto contact lenses and hydrated to provide contact lenses ranging inwater content from 20 to about 48. The Dk's of these lenses ranged fromabout 19 to 66 (FATT method).

EXAMPLE 19

The macromonomer of Example 2 was combined with hydrophilic monomers asindicated in Table 2, below. Specifically, soft contact lensescomprising this macromonomer at 33% by weight of the final contact lenscopolymer were copolymerized with a mixture of HEMA (33.5%), VP (33.1%)and EGDM (0.4%). After mixing the macromonomer and monomers, the mixturewas placed in molds under UV light in the absence of oxygen forapproximately 1 hour. After removing the buttons from the molds, thecopolymers were then machined into contact lenses and hydrated toprovide contact lenses having a water content of about 31. The Dk ofthese lenses was about 20 (FATT method).

EXAMPLE 20

The star polymer of Example 3 was combined with hydrophilic monomers asindicated in Table 2, below. Specifically, soft contact lensescomprising this star polymer at 27.6% by weight of the final contactlens copolymer were copolymerized with a mixture of HEMA (28%), MAA(16%), VP (28%) and EGDM (0.4%). After mixing the macromonomer andmonomers, the mixture was placed in molds under UV light in the absenceof oxygen for approximately 1 hour. After removing the buttons from themolds, the copolymers were then machined into contact lenses andhydrated to provide contact lenses having a water content of 20. The Dkof these lenses was about 29 (FATT method).

EXAMPLE 21

The star polymer of Example 7 was combined with hydrophilic monomers asindicated in Table 2, below. Specifically, soft contact lensescomprising this star polymer at 35% by weight of the final contact lenscopolymer were copolymerized with a mixture of HEMA (30%), VP (34.8%)and EGDM (0.2%). After mixing the macromonomer and monomers, the mixturewas placed in molds under heat (60° C. for 24 hours, followed by 110° C.for 24 hours. After removing the buttons from the molds, the copolymerswere then machined into contact lenses and hydrated to provide contactlenses having a water content of 45. The Dk of these lenses was about 67(FATT method).

EXAMPLE 22

The star polymer of Example 6 was combined with hydrophilic monomers asindicated in Table 2, below. Specifically, soft contact lensescomprising this star polymer at 30% by weight of the final contact lenscopolymer were copolymerized with a mixture of VP (69.5%) and EGDM(0.5%). After mixing the macromonomer and monomers, the mixture wasplaced in molds under UV light for one hour followed by heat (60° C. for18 hours, followed by 110° C. for 18 hours. After removing the buttonsfrom the molds, the copolymers were then machined into contact lensesand hydrated to provide contact lenses having a %water of 80. The Dk ofthese lenses was about 131 (FATT method).

EXAMPLE 23

The star polymer of Example 8 was combined with hydrophilic monomers asindicated in Table 2, below. Specifically, soft contact lensescomprising this star polymer at 33% by weight of the final contact lenscopolymer were copolymerized with a mixture of HEMA (33%), VP (34%) andEGDM (0.5%). After mixing the macromonomer and monomers, the mixture wasplaced in molds under heat and pressure (60° C. for 7 hours, followed by110° C. for 24 hours). After removing the buttons from the molds, thecopolymers were then machined into contact lenses and hydrated toprovide contact lenses having a %water of 43. The Dk of these lenses wasabout 64 (FATT method).

EXAMPLE 24

The star polymer of Example 6 was combined with hydrophilic monomers asindicated in Table 2, below. Specifically, soft contact lensescomprising this star polymer at 49.5% by weight of the final contactlens copolymer were copolymerized with a mixture of HEMA (25%), VP (25%)and EGDM (0.5%). After mixing the macromonomer and monomers, the mixturewas placed in molds under UV light for 45 minutes followed by heat (75°C. for 8 hours, followed by 110° C. for 12 hours). After removing thebuttons from the molds, the copolymers were then machined into contactlenses and hydrated to provide contact lenses having a % water of 17.The Dk of these lenses was about 73 (FATT method).

EXAMPLE 25

The macromonomer of Example 13 was combined withhydroxyethylmethacrylate (HEMA) and methacrylic acid (MAC) (from 0 to 3%by weight) as indicated in Table 3, below. In one example,ethyleneglycol dimethacrylate (EDGMA), 0.5% by weight, was also added.Soft contact lenses comprising this macromonomer (30% by weight of thefinal contact lens copolymer) were made by copolymerizing a mixture ofthe above-mentioned monomers (using 3% Irgacure 500 and a Dymax highintensity UV unit as previously described for 30 minutes inpolypropylene lens molds. After removing the lenses from the lens molds,the copolymers were then hydrated (0.1M phosphate buffer pH of 7.5-8.0)to provide contact lenses having water cotents ranging from 27% to about55%. The Dk (normalized for varying thicknesses) of these lenses rangedfrom 28.5 to 49.1. These results are presented in Table 3, below.

EXAMPLE 26

The macromonomer of Example 12 was combined withhydroxyethylmethacrylate (HEMA) and methacrylic acid (MAC) (from 0 to 8%by weight) as indicated in Table 4, below. Soft contact lensescomprising this macromonomer (30% by weight of the final contact lenscopolymer) were made by copolymerizing a mixture of the above-mentionedmonomers (using 3% Darocur 1173 and a Dymax high intensity UV unit aspreviously described for 30 minutes in polypropylene lens molds). Afterremoving the lenses from the lens molds, the copolymers were thenhydrated (0.1M phosphate buffer pH of 7.5-8.0) to provide contact lenseshaving water contents ranging from 23.4% to about 65%. The Dk(normalized for varying thicknesses) of these lenses ranged from about17 to 62.

EXAMPLE 27

The macromonomer of Example 12 was combined withhydroxyethylmethacrylate (HEMA), vinyl pyrrolidone (VP) and ethyleneglycol dimethacrylate (EGDMA) as indicated in Table 5, below. In oneexample lens 2.0% methacrylic acid was added. Soft contact lensescomprising this macromonomer (30% by weight of the final contact lenscopolymer) were made by copolymerizing a mixture of the above-mentionedmonomers (using 0.5% Darocur 173 or 0.5% Irgacure 500 and a lowintensity UV unit as previously described) for 90 minutes inpolypropylene lens molds. After removing the lenses from the lens molds,the copolymers were then hydrated (0.1M phosphate buffer pH of 7.5-8.0)to provide contact lenses having water cotents ranging from 43% to about62%. The Dk (normalized for varying thicknesses) of these lenses rangedfrom about 30 to 78.

EXAMPLE 28

The macromonomer of Example 12 was combined withhydroxyethylmethacrylate (HEMA) and methacrylic acid (MAC) (from to 4%by weight) as indicated in Table 6, below. Soft contact lensescomprising this macromonomer (20% or 40% by weight of the final contactlens copolymer) were made by copolymerizing a mixture of theabove-mentioned monomers (using 0.5% Daracure 1173 and a low intensityUV unit as previously described) for 90 minutes in polypropylene lensmolds. After removing the lenses from the lens molds, the copolymerswere then hydrated (0.1M phosphate buffer pH of 7.5-8.0) to providecontact lenses having water cotents ranging from about 20% to about 59%.The Dk (normalized for varying thicknesses) of these lenses ranged fromabout 21 to about 81.

EXAMPLE 29

The macromonomer of Example 12 was combined withhydroxyethylmethacrylate (HEMA), methacrylic acid (MAC) andN-isobutoxymethylacrylamide (IBMA) as indicated in Table 7, below. Softcontact lenses comprising this macromonomer (20-30% by weight of thefinal contact lens copolymer) were made by copolymerizing a mixture ofthe above-mentioned monomers (using 3.0% Daracure 1173 and a highintensity UV unit as previously described) for about 30 minutes onpolypropylene film molds. After removing the films from the film molds,the copolymers were then hydrated (0.1M phosphate buffer pH of 7.5-9.0)to provide contact lenses having water cotents ranging from about 50% toabout 60%. The Dk (normalized for varying thicknesses) of these lensesranged from 29.8 to about 130.

EXAMPLES 30-32

The following Examples 30-32 compare compositions containingmacromonomers and star polymers without additional silicone acrylatebeing added to the mixture of monomers with compositions which containadditional monomeric silicone acrylate according to the presentinvention.

In Examples 30-32 compositions were made by adding macromonomer or starpolymer to a mixture of monomers to produce prepolymerized compositions.The pre-polymerized compositions are thereafter polymerized as set forthbelow. Viscosities were determined on pre-polymerized compositions in aGardner Cargille Viscosity Tube (available from the Paul N. GarnderCompany, Inc., Pompano Beach, Fla., U.S.A.) using the Time-Method (ASTMD1545) by timing bubble speed between the 100 mm and 27 mm marks.

EXAMPLE 30

The macromonomer of Example 12 was combined withhydroxyethylmethacrylate (HEMA), methacrylic acid (MAC) and EGDMA asindicated in Table 8, below. Soft contact lenses and lens materialscontaining this macromonomer (25 or 30% by weight of the final contactlens composition), were made by copolymerizing a mixture of theabove-mentioned monomers and macromoner, and in certain cases 16.66weight percent of eitherTris(trimethylsiloxy-3-methacryloxypropylsilane) (TRIS) or3-[3-methacryloxypropyl-1,3,3-tris(trimethylsiloxy)-1-methyl-1-vinyldisiloxane)(VIN) as indicated. In the case of the composition which did not containany silicone acrylate, films or lenses were produced in polypropylenemolds using approximately 0.4% Darocur 1173 and a medium intensity UVlight source (365 nm) for approximately 15-30 minutes. In the case ofthe composition which contained 16.66% TRIS, films or lenses wereproduced in polypropylene molds or flats using about 0.5% Darocur 1173and 0.5% Irgacure 651 and a medium intensity UV light source (365 nm) oralternatively, about 1% Darocur 1173 and a high intensity light source(Dimax unit). Polymer rods containing 16.66% TRIX may also be producedusing heat polymerization conditions and initiators 0.5% t-butylperoctoate, 0.5% Vazo 52 and 0.2% t-butylperoxybenzoate (35° C. -100° C.in steps over several days). In the case of the composition whichcontained 16.66% VIN, films and buttons were polymerized using acombination of 0.4% Darocur 1173, 0.4% Irgacure 651, 0.4%t-butylperoctoate and 0.4% Vazo 52 under low intensity UV light for 15minutes, under high intensity UV light for a further 15 minutes andfinally under heat at 80° C. for 3 hours.

After removing the films from the film molds and the lenses from lensmolds, the compositions were then hydrated (0.1M phosphate buffer pH of7.5-9.0) to provide wettable soft contact lens materials having watercontents ranging from about 35% to about 50%. The Dk (normalized forvarying thicknesses) of these lenses ranged from about 27 to about 65.After normalizing for the different water contents (for example, thetrue Dk of the 35.75% water content material containing 16.66% VIN isapproximately 45+, the results set forth in Table 8 evidence that theinclusion of silicone acrylate markedly enhances the Dk and dramaticallylowers the viscosity of the prepolymerized compositions.

EXAMPLE 31

The star polymers of Examples 4 and 6 were combined withhydroxyethylmethacrylate (HEMA), methacrylic acid (MAC) and EGDMA asindicated in Table 9, below. Soft contact lens materials containingthese star polymers (25 or 30% by weight of the final contact lenscomposition), were made by copolymerizing a mixture of theabove-mentioned monomers and star polymers, and in certain cases, 16.66weight percent of Tris(trimethylsiloxy-3-methacryloxypropylsilane)(TRIS) as indicated in polypropylene film molds. All compositions werepolymerized using the same conditions and initiators. Each compositioncontained 0.4% Darocur 1173 and 0.4% Irgacure 651 and was polymerizedfirst under a low intensity UV light for 45 minutes followed by 15minutes under a high intensity UV light source (Dimax unit).

After removing the films from the film molds, the compositions were thenhydrated (0.1M phosphate buffer pH of 7.5-9.0) to provide contact lensmaterials having water contents ranging from about 50% to about 60%. TheDk (normalized for varying thicknesses) of these lenses ranged fromabout 39 to about 61. The results set forth in Table 9 evidence that theinclusion of silicone acrylate markedly enhances the Dk and dramaticallylowers the viscosity (factor of 100-200) of the prepolymerizedcompositions.

EXAMPLE 32

The macromonomers of Examples 13 and 14 were combined withhydroxyethylmethacrylate (HEMA), methacrylic acid (MAC) and EGDMA asindicated in Table 10, below. Soft contact lens materials containingthese macromonomers (25 or 30% by weight of the final contact lenscomposition), were made by copolymerizing a mixture of theabove-mentioned monomers and macromonomers, and in certain cases, 16.66weight percent of Tris(trimethylsiloxy-3-methacryloxypropylsilane)(TRIS) in polypropylene film molds as indicated in Table 10. Themacromonomer from Example 12 and monomers was also made in contact lensmolds. All compositions were polymerized using the same initiators andconditions. Each composition contained 0.4% Darocur 1173 and 0.4%Irgacure 651 and was polymerized first under a low intensity UV lightfor 45 minutes followed by 15 minutes under a high intensity UV lightsource (Dimax unit).

After removing the films from the film molds, the compositions were thenhydrated (0.1M phosphate buffer pH of 7.5-9.0) to provide contact lensmaterials having water contents ranging from about 50% to about 60%. TheDk (normalized for varying thicknesses) of these lenses ranged fromabout 21 to about 54. The results set forth in Table 9 evidence that theinclusion of silicone acrylate markedly enhances the Dk and dramaticallylower the viscosity (factor of 20-30) of the prepolymerizedcompositions.

I. COMPARISON OF CONVENTIONAL SOFT LENSES AND LENSES OF THE PRESENTINVENTION

Conventional soft lenses are generally copolymers of hydrophilicmonomers such as hydroxyethyl methacrylate, methacrylic acid and N-vinylpyrrolidone. The following Table I gives the literature value of oxygenpermeabilities versus water content of convention soft lenses. Asindicated, permeabilities increase as a function of an increase in watercontent.

                  TABLE 1                                                         ______________________________________                                        Literature Value of Water Content vs. Permeability                            The following represents the calculated Dk of a series of standard            hydrophilic contact lens materials at the indicated water                     content. The true Dk for different water content soft contact                 lens materials follows the general equation:                                  Dk = 2 × e.sup.0.041 × water content                               Water Content                                                                             ##STR13##                                                        ______________________________________                                        20          4.54                                                              25          5.57                                                              30          6.84                                                              35          8.39                                                              40          10.31                                                             45          12.65                                                             50          15.53                                                             55          19.07                                                             60          23.40                                                             65          28.73                                                             70          35.27                                                             75          43.29                                                             80          53.15                                                             85          65.24                                                             ______________________________________                                    

Table 1 tracks the composition, water content and permeabilities of someconventional soft contact lenses.

Tables 2-10 Soft Contact Lenses According to the Present Invention

The addition of pre-formed silicone containing polymers improves thepermeability vs the water content of soft lenses. The following Tables2-7 gives the properties of lenses made with block, linear polymers andstar polymers. As can be seen from these results, the inclusion of thesepolymers dramatically improves the permeability of lenses at comparablewater contents. Many of these lenses are drapeable and exhibit favorableadditional characteristics as well.

                                      TABLE 2                                     __________________________________________________________________________    Permeability vs Water Content for Lenses Made with                            Macromonomers and Star Polymers                                               Composition                      PERM.                                        Lens Ex.                                                                           Poly.                                                                             HEMA MAC  VP EGDM  % Water                                                                            Dk(× 10.sup.-11)                       __________________________________________________________________________    15   33  33.5 --   33 0.5   39   45                                           16   33  20   --   46.6                                                                             0.4   48   66                                           17   27.6                                                                              28   --   28 0.4   20   19                                           18   21.5                                                                              36.9 41.3 -- 0.3   26   24                                           19   33  33.5 --   33.1                                                                             0.4   31   20                                           20   27.6                                                                              28   16   28 0.4   20   29                                           21   35  30   --   34.8                                                                             0.2   45   67                                           22   30  --   --   69.5                                                                             0.5   80   131                                          23   33  33   --   34 0.5   43   64                                           24   49.5                                                                              25   --   25 0.5   17   73                                           __________________________________________________________________________

                  TABLE 3                                                         ______________________________________                                        Permeability vs Water Content for Lenses Made with                            Macromonomers As set Forth in Example 25                                      Macro-                                                                        monomer                                                                              HEMA     MAC     EGDMA  H2O Content                                                                            True Dk                               ______________________________________                                        30     70       0       --     33       29                                    30     69       1       --     27       28                                    30     68       2       --     43.8     43                                    30     66.5     3       0.5    55       49                                    ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Permeability vs Water Content for Lenses Made with                            Macromonomers As Set Forth in Example 26                                      Macromonomer                                                                            HEMA      MAC     H2O Content                                                                             True Dk                                 ______________________________________                                        30        70        0       23.4      17                                      30        68        2       40.6      34                                      30        66        4       51.9      54                                      30        64        6       59        52                                      30        66        8       65        62                                      ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Permeability vs Water Content for Lenses Made with                            Macromonomers As Set Forth in Example 27                                      Macro-                              H2O                                       monomer                                                                              VP     HEMA     MAC   EGDMA  Cont. True Dk                             ______________________________________                                        30     49.5   20       --    0.5    47.5  30                                  30     69.5   --       --    0.5    62    78                                  30     32.8   34.8     2     0.5    43    38                                  ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Permeability vs Water Content for Lenses Made with                            Macromonomers As Set Forth in Example 28                                      Macromonomer                                                                            HEMA      MAC     H2O Content                                                                             True Dk                                 ______________________________________                                        20        80        0       27        21                                      20        78        2       45.5      31                                      20        76        4       58.5      81                                      40        80        0       20        24                                      ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Permeability vs Water Content for Films Made with                             Macromonomers As Set Forth in Example 29                                      Macro-                                                                        monomer                                                                              HEMA     MAC      IBMA  H2O Content                                                                            True Dk                               ______________________________________                                        20     51       6        20    52       30                                    25     46       6        20    55       50                                    30     41       6        20    60       130                                   ______________________________________                                    

The results of the incorporation of silicone-containing pre-formedacrylic copolymers according to the present invention into soft lenspolymer matrices evidenced surprisingly enhanced gas permeability (TrueDk- measured Dk normalized for thickness variation) relative to the gaspermeability of conventional contact lenses. For a given water content,the lenses of the present invention exhibited oxygen permeabilitieswhich were at least about 1.5-2 times the permeabilities exhibited bythe conventional lens. As can be seen from these results the inclusionof these polymers dramatically improves the permeability of lenses atcomparable water contents. In addition, many of these lenses aredrapeable and exhibit toughness/durability as well. Moreover, many ofthese lenses are optically clear, having light transmissions approaching100% (>95%).

II. COMPARISON OF SOFT CONTACT LENS MATERIALS CONTAINING PREFORMEDCOPOLYMER OR PREFORMED COPOLYMER AND ADDITIONAL MONOMERIC SILICONACRYLATE

                                      TABLE 8                                     __________________________________________________________________________    Permeability vs Water Content for Films Made with                             Macromonomers As Set Forth in Example 30                                      Macro. Ex. 12                                                                         HEMA MAC Sil. Ac.                                                                           EGDMA                                                                              H2O Cont.                                                                           True Dk                                                                            Viscos.                                 __________________________________________________________________________    30      67.2 2.5 --    0.3%                                                                              50    35   3940                                    25      56   2.1 16.66                                                                              0.25 48    65   152                                                      TRIS                                                         25      56   2.1 16.66                                                                              0.25 36    27   238                                                      VIN                                                          __________________________________________________________________________

The data set forth in Table 8 evidences that the inclusion of siliconeacrylate substantially enhances the Dk of the material includingmacromonomer as well as significantly reducing the viscosity of theprepolymerized composition which may be used in spin-casting systems.

                                      TABLE 9                                     __________________________________________________________________________    Permeability vs Water Content for Films Made with                             Star Polymers As Set Forth in Example 31                                      Star Ex.                                                                           Wt. %                                                                             HEMA MAC TRIS                                                                              EGDMA                                                                              H2O Cont.                                                                           True Dk                                                                            Viscos.                                 __________________________________________________________________________    Ex. 4                                                                              30  67.2 2.5 --  0.3% 49.3  39.5 516.2                                   Ex. 4                                                                              25  56   2.1 16.66                                                                             0.25%                                                                              43.4  49.8  2.3                                    Ex. 6                                                                              30  67.2 2.5 --  0.3% 59.7  51.0 663.8                                   Ex. 6                                                                              25  56   2.1 16.66                                                                             0.25%                                                                              51.8  60.9  5.1                                    __________________________________________________________________________

The data set forth in Table 9 evidences that the inclusion of siliconeacrylate substantially enhances the Dk of the material including starpolymer as well as significantly (by a factor of about 100-200) reducingthe viscosity of the prepolymerized composition.

                                      TABLE 10                                    __________________________________________________________________________    Permeability vs Water Content for Films Made with                             Macromonomers As Set Forth in Example 32                                      Macro Ex.                                                                           Wt. %                                                                             HEMA MAC TRIS                                                                              EGDMA                                                                              H2O Cont                                                                            True Dk                                                                            Viscos.                                __________________________________________________________________________    Ex. 13                                                                              30  67.2 2.5 --  0.3% 44    23.3 35.27                                  Ex. 13                                                                              25  56   2.1 16.66                                                                             0.25%                                                                              42    43.3 1.0                                    Ex. 14                                                                              30  67.2 2.5 --  0.3% 56    29.41                                                                              25+*                                   Ex. 14                                                                              25  56   2.1 16.66                                                                             0.25%                                                                              53    53.8 1.4                                    __________________________________________________________________________     *Estimated viscosity number  not performed.                              

The data set forth in Table 10 evidences that the inclusion of siliconeacrylate substantially enhances the Dk of the material includingmacromonomer of defined structure as well as significantly reducing theviscosity of the prepolymerized composition which may be used inspin-casting systems.

This invention has been described in terms of specific embodiments setforth in detail herein, but it should be understood that these are byway of illustration and the invention is not necessarily limitedthereto. Modifications and variations will be apparent from thedisclosure and may be resorted to without departing from the spirit ofthe inventions those of skill in the art will readily understand.Accordingly, such variations and modifications are considered to bewithin the purview and scope of the invention and the following claims.

What is claimed is:
 1. A composition comprising at least about 20% byweight of at least one linear diblock macromonomer comprising about 20%to about 70% by weight of at least one hydrophilic block, saidhydrophilic block consisting essentially of monomeric units derived fromat least one hydrophilic acrylic monomer and about 30% to about 80% byweight of at least one hydrophobic, permeable block, said hydrophobicblock comprising about 80% to about 100% by weight of monomeric unitsderived from at least one silicone acrylate, said composition comprisingno more than about 75% by weight of a matrix formed from the randompolymerization of a mixture of monomers, said composition before saidpolymerization including about 5% to about 45% by weight of at least onesilicone acrylate, said mixture of monomers including an amount ofhydrophilic monomer effective to provide a final composition which uponhydration comprises at least about 10% by weight water, said compositionafter hydration being clear and wettable, said macromonomer beingcopolymerized throughout said matrix.
 2. A composition comprising about20% to about 60% by weight of at least one linear diblock macromonomerand about 35% to about 75% by weight of a matrix formed from the randompolymerization of a mixture of monomers in combination with saidmacromonomer, said macromonomer comprising about 20% to about 70% byweight of at least one hydrophilic block, said hydrophilic blockcomprising about 80% to about 100% by weight of monomeric units derivedfrom at least one hydrophilic acrylic monomer and about 30% to about 80%by weight of at least one hydrophobic, permeable block, said hydrophobicblock comprising about 80% to about 100% by weight silicone acrylatemonomeric units, said mixture of monomers comprising at least onehydrophilic monomer in an amount effective to provide a compositionwhich comprises at least about 23% to about 65% by weight water afterhydration, said composition also comprising about 5% to about 45% byweight of monomeric silicone acrylate before said polymerization, saidcomposition after hydration being clear and wettable, said macromonomerbeing copolymerized throughout said matrix.
 3. The composition accordingto claim 2 wherein said silicone acrylate units of said macromonomer arederived from at least one silicone acrylate having the general formula:##STR14## where A is selected from the group consisting of C1-C5 alkylgroups, phenyl groups, and G groups; G is a group of the structure:##STR15## D and E are selected from the class consisting of C1-C5 alkylgroups, phenyl groups and G groups; m is an integer from one to five,except where A, D and E are C₁ alkyl groups, m is an integer from 1 to15; R₂ is H or CH₃ and n is an integer from one to three.
 4. Thecomposition according to claim 3 wherein said composition beforepolymerization includes at least about 5% by weight of monomericsilicone acrylate having the general formula: ##STR16## where A isselected from the group consisting of C1-C5 alkyl groups, phenyl groups,and G groups; G is a group of the structure: ##STR17## D and E areselected from the group consisting of C1-C5 alkyl groups, phenyl groupsand G groups; m is an integer from one to five, except where A, D and Eare C₁ alkyl groups, m is an integer from 1 to 15; R₂ is H or CH₃ and nis an integer from one to three.
 5. The composition according to claim 4wherein said silicone acrylate units are derived fromTRIS(trimethylsiloxy)-3-methacryloxypropylsilane.
 6. The compositionaccording to claim 4 wherein said monomeric silicone acrylate isTRIS(trimethylsiloxy)-3-methacryloxypropylsilane.
 7. The compositionaccording to claim 4 wherein m is an integer from 1 to
 7. 8. Thecomposition according to claim 3 wherein m is an integer from 1 to
 7. 9.The composition according to claim 3 wherein said hydrophilic blockcomprises units of hydrophilic monomers selected from the groupconsisting of hydroxyethyl methacrylate, glycerol methacrylate,methacrylic acid and mixtures thereof.
 10. The composition according toclaim 4 wherein said matrix further comprises units of a crosslinkingmonomer in an amount ranging from about 0.05% to about 3.0% by weight ofsaid matrix.
 11. The composition according to claim 2 wherein saidhydrophilic monomer in said mixture of monomers is selected from thegroup consisting of methacrylic acid, N-vinyl pyrrolidone,glycerolmethacrylate, hydroxyethyl methacrylate, and mixtures thereof.12. The composition according to claim 6 wherein said hydrophilic blockis derived from a mixture of hydroxyethyl methacrylate and a minoramount of methyl methacrylate.
 13. The composition according to claim 2wherein said mixture of matrix monomers comprises a mixture ofhydroxyethyl methacrylate and methacrylic acid, a mixture ofhydroxyethyl methacrylate, methacrylic acid and N-vinylpyrrolidone, amixture of N-vinylpyrrolidone and methylmethacrylate or a mixture ofN-vinylpyrrolidone and hydroxyethyl methacrylate.
 14. The compositionaccording to claim 2 wherein said macromonomer before polymerization ofsaid composition contains at least one pendant organo group containing apolymerizable double bond selected from the group consisting ofmethacryloxy, acryloxy, styrenic and allylic and said group is attachedto the in the hydrophilic block by means of a chemical linkage selectedfrom the group consisting of urethane, ester, ether and amide linkages.15. A contact lens manufactured from a composition according to any oneof claim 2, 3-10, 11-12 and 13-14.
 16. The contact lens according toclaim 15 which is manufactured by a spin-casting process.